Anti-fouling composition comprising an aerogel

ABSTRACT

The present invention also relates to an anti-fouling composition comprising one or more aerogels. In one embodiment the aerogel encapsulate one or more bioactive agents. The one or more encapsulated bioactive agents can in one preferred embodiment be released from the aerogel over time. In one embodiment the encapsulated bioactive agents comprise one or more enzymes. In one preferred embodiment the anti-fouling composition comprising one or more aerogels is a coating composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/742,464 filed Jun. 28, 2010, which is the U.S. national phase ofPCT/DK2008/050272 filed Nov. 12, 2008, which claims priority of DanishPatent Application No. PA 2007 01594 filed Nov. 12, 2007; U.S.Provisional Application No. 60/987,221 filed Nov. 12, 2007; U.S.Provisional Application No. 61/059,353 filed Jun. 6, 2008; and EuropeanPatent Application No. 08157766.0 filed Jun. 6, 2008.

All patent and non-patent references cited in the application, or in thepresent application, are also hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

Aerogels

Aerogel is a low-density solid-state material derived from gel in whichthe liquid component of the gel has been replaced with gas. The resultis a low density solid with several characteristic properties such asits effectiveness as an insulator.

Aerogel was first created by Steven Kistler in 1931. Aerogels are ingeneral produced by extracting the liquid component of a gel throughsupercritical drying. This allows the liquid to be slowly drawn offwithout causing the solid matrix in the gel to collapse from capillaryaction, as would happen with conventional evaporation. The firstaerogels were produced from silica gels. Aerogels based on alumina,chromia and tin oxide have also been described. Carbon aerogels weredeveloped in the early 1990s.

Anti-Fouling Agents

In order to minimize the impacts of foulers, many underwater structuresare protected by antifouling coatings. Coatings, however, have beenfound to be toxic to marine organisms. For example, extremely lowconcentrations of tributyltin moiety (TBT), the mostly commonly usedanti-fouling agent, cause defective shell growth in the oysterCrassostrea gigas (at a concentration of 20 ng/l) and development ofmale characteristics in female genitalia in the dog whelk Nucellalapillus (where gonocharacteristic change is initiated at 1 ng/l). Theban of organotins such as TBT and triphenyltin (TPT), and other toxicbiocides in marine coatings is a severe problem for the shippingindustry; it presents a major challenge for the producers of coatings todevelop alternative technologies to prevent fouling on ship hulls. Safermethods of biofouling control are actively researched. Copper andderivative compounds have successfully been used either in paints or asmetal sheeting (for example Muntz metal which was specifically made forthis purpose), though there is still debate as to the safety of copper.

SUMMARY OF THE INVENTION

The present invention relates to an aerogel. The present invention alsorelates to an anti-fouling composition comprising one or more aerogels.In one embodiment the aerogel encapsulate one or more bioactive agents.The one or more encapsulated bioactive agents can in one preferredembodiment be released from the aerogel over time. In one embodiment theencapsulated bioactive agents comprises enzymes.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a photograph showing a series of test panels which were usedto evaluate the coatings of the present invention.

DEFINITIONS

Aerogel is a low-density solid-state material derived from gel in whichthe liquid component of the gel has been replaced with gas.

Anti-fouling is the process of removing or inhibiting the accumulationof biofouling.

Antifouling species: Any species exerting antifouling effect. Speciessuch as antimicrobial species, antibacterial species, antifungalspecies, biocides, biorepellents, and the like. Bioactive agents andantifouling species are used interchangeable herein.

Bio-film: Habitation of microbial organisms on a solid or semi-solidsurface.

Biofouling or biological fouling is the undesirable accumulation ofmicroorganisms, plants, algae, and animals on surfaces such as submergedstructures like ships' hulls. Subtilisins comprises a family of serineproteases isolated from bacillus subtilis. Anti-fouling: The effect ofcontrolling, reducing and/or eliminating over time the number ofundesirable microorganisms in a bio-film.

Coating composition: Composition for coating an object, such as a paint.

Co-factor: Additional factor required by an enzyme.

Compound: Substrate for an enzyme capable of catalysing said compound,wherein said catalysis results in the formation of an antimicrobialspecies comprising an antimicrobial activity.

Enzyme: Biomolecule comprising a plurality of amino acids and capable ofcatalysing conversion of substrates into products. The terms enzyme andprecursor enzyme are used interchangably unless otherwise indicated. Anenzyme is acting on a compound as defined herein when said actiongenerates an antifouling species having antifouling activity. Aprecursor enzyme is any enzyme capable of providing to the enzyme, bymeans of degradation or otherwise, a substrate for said enzyme in theform of said compound.

Lipid or lipid composition: When used herein in connection withmodification and/or coating of enzymes, lipid means a compound having along-chain alkyl group, which is a hydrophobic group, and a hydrophilicgroup.

Marine organism: Any organism capable of habitating in an aqueousenvironment, including organisms capable of forming undesirablebio-films.

Microbial organism: Any organism belonging to the classes of prokaryotesand lower eukaryotes, including bacteria, yeasts, fungal cells and slimemolds.

Oxidase: Enzyme the activity of which results in an oxidation, includingan oxidation resulting in the formation of a peroxide, includinghydrogenperoxide.

Paint is any liquid, liquifiable, or mastic composition which afterapplication to a surface in a thin layer is converted to an opaque solidfilm.

Painting is the application of paint.

Peroxide: Product resulting from a reaction involving an oxidase.

Precursor compound: Precursor compounds are capable of being catalysedby a precursor enzyme, wherein said catalysis results in the formationof a compound capable of being catalysed by an enzyme under thegeneration of an antifouling species, including an antimicrobial specieshaving an antimicrobial activity.

Secretion: Process of translocating a compound or precursor compoundacross the outer membrane of a microbial species. Secretion applies tocompounds which remain membrane associated and to compounds which aresubsequently released into an external environment.

Surface: Outer part of e.g. a microbial organism in contact with theexternal environment.

Xerogel: A xerogel is a solid formed from a gel by drying withunhindered shrinkage. Xerogel usually retains high porosity (25%) andenormous surface area (150-900 m²/g), along with very small pore size(1-10 nm). When solvent removal occurs under hypercritical(supercritical) conditions, the network does not shrink and a highlyporous, low-density material known as an aerogel is produced. Heattreatment of a xerogel at elevated temperature produces viscoussintering and effectively transforms the porous gel into a dense glass.

DETAILED DESCRIPTION OF THE INVENTION

The present invention in one embodiment relates to a compositioncomprising a xerogel and at least one enzyme capable of acting on acompound, wherein said action results in the formation of an antifoulingspecies comprising an antifouling activity. The compound can form partof said composition, but it does not need to form part of saidcomposition. The latter is the case when the compound is e.g. providedby an external environment in which the composition is exerting anantifouling effect. The composition is preferably has a self-polishingeffect.

The present invention in another embodiment relates to a compositioncomprising an aerogel and at least one enzyme capable of acting on acompound, wherein said action results in the formation of an antifoulingspecies comprising an antifouling activity. The compound can form partof said composition, but it does not need to form part of saidcomposition. The latter is the case when the compound is e.g. providedby an external environment in which the composition is exerting anantifouling effect. The composition is preferably has a self-polishingeffect.

The composition can be a coating composition further comprising apigment, or a hygienic composition further comprising a fragrance, or acomposition as stated herein above further comprising both a pigment anda fragrance.

In another embodiment there is provided a method for preparing suchcompositions, including a coating composition, as well as uses of such acoating composition, including uses as described in more detail hereinbelow.

In yet another embodiment of the invention there is provided a methodfor reducing marine corrosion comprising the step of coating a marinesurface with a marine antifouling composition, whereby the compositionforms at least one film that reduces adsorption of corrosive moleculesto the surface. Also disclosed is a method wherein the compositionimpedes surface corrosion and intergranular corrosion.

In a still further embodiment of the invention there is provided amethod for reducing marine corrosion comprising the step of coating amarine surface with a marine antifouling paint, whereby the paint formsat least one film that reduces adsorption of corrosive molecules to thesurface. In yet another embodiment of the claimed invention, a method isdisclosed, wherein the paint impedes surface corrosion and intergranularcorrosion.

In an even further embodiment of the invention there is provided amethod for limiting absorption of water by a marine surface comprisingthe step of coating the surface with a marine antifouling composition ormarine antifouling paint, whereby the composition or paint produces afilm which in turn reduces the porosity of the surface.

In still another embodiment of the invention, a method is disclosed forreducing the coefficient of drag of a marine surface comprising the stepof coating the surface with a marine antifouling composition or marineantifouling paint. The invention is also directed to methods of usingthe marine antifouling composition or marine antifouling paint whereinsurfactants capable of acting as wetting agents are produced bymicroorganisms in contact with the composition or paint.

Yet another embodiment of the invention is directed to a method forremoving marine growth from a marine surface, comprising the step ofcoating the surface with a marine antifouling composition or marineantifouling paint. Another embodiment of the invention is a method ofusing the marine antifouling composition or marine antifouling paintwherein the marine growth is hard or soft growth.

An even further embodiment of the invention is directed to a method ofusing the marine antifouling composition or marine antifouling paint,wherein e.g. hydrolytic enzymes attack exudates of existing growths andcauses release of hard and soft growth.

Types of Aerogels:

In one embodiment the present invention relates to silica aerogels gelsor carbon aerogels. Alternatively the aerogels are based on alumina,chromia, tin and bromo oxide.

Metal-aerogel nanocomposites can be prepared by impregnating thehydrogel with solution containing ions of the suitable noble ortransition metals. The impregnated hydrogel is then, in one embodiment,irradiated with gamma rays, leading to precipitation of nanoparticles ofthe metal. Such composites can be used as eg. catalysts, sensors,electromagnetic shielding, and in waste disposal. A prospective use ofplatinum-on-carbon catalysts is in fuel cells.

Carbon aerogels are used in the construction of small electrochemicaldouble layer supercapacitors. Due to the high surface area of theaerogel, these capacitors can be 2000 to 5000 times smaller thansimilarly rated electrolytic capacitors. Aerogel supercapacitors canhave a very low impedance compared to normal supercapacitors and canabsorb/produce very high peak currents.

Aerogel Composition:

The aerogel may be composed of any material used in prior art or anycombination thereof.

The aerogel may be prepared using various oxide units in order to addproperties required as additional to the storage and release ofproteins. The invention includes silicon/titania; silicon/borate-;silicon/zirkonate but is not limited to these.

The aerogel may be adjusted by its composition to have hydrophilic orhydrophobic properties by use of a combination of silicate and dialkylsilicate units. The mixture can be in the range 100:0 to 80:20 such assuch as 98:2, for example 96:4, such as 95:5, for example 94:6, such as92:8, for example 90:10, such as 88:12, for example 86:14, such as85:15, for example 84:16, such as 82:18. In one preferred embodiment themixture can be in the range 95:5.

Production of Aerogels:

Silica aerogel is made by drying a hydrogel composed of colloidal silicain an extreme environment. Specifically, the process starts with aliquid alcohol like ethanol which is mixed with a silicon alkoxideprecursor to form a silicon dioxide sol gel (silica gel). Then, througha process called supercritical drying, the alcohol is removed from thegel. This is typically done by exchanging the ethanol for liquidacetone, allowing a better miscibility gradient, and then onto liquidcarbon dioxide and then bringing the carbon dioxide above its criticalpoint. A variant on this process involves the direct injection ofsupercritical carbon dioxide into the pressure vessel containing theaerogel. The end result removes all liquid from the gel and replaces itwith gas, without allowing the gel structure to collapse or lose volume.

Aerogel composites have been made using a variety of continuous anddiscontinuous reinforcements. The high aspect ratio of fibers such asfiberglass have been used to reinforce aerogel composites withsignificantly improved mechanical properties.

Resorcinol-formaldehyde aerogel (RF aerogel) is made in a way similar toproduction of silica aerogel.

Carbon aerogel is made from a resorcinol-formaldehyde aerogel by itspyrolysis in inert gas atmosphere, leaving a matrix of carbon. It iscommercially available as solid shapes, powders, or composite paper.

Physical and Chemical Properties of Aerogels:

In one preferred embodiment the density of the aerogel is in the rangefrom 0.05 to 1.0 g/mol such as 0.05 g/mol to 0.45 g/mol, for example0.05 g/mol to 0.4 g/mol, such as 0.05 g/mol to 0.35 g/mol, for example0.05 g/mol to 0.3 g/mol, such as 0.05 g/mol to 0.35 g/mol, for example0.05 g/mol to 0.3 g/mol, such as 0.05 g/mol to 0.25 g/mol, for example0.05 g/mol to 0.2 g/mol, such as 0.05 g/mol to 0.15 g/mol, for example0.05 g/mol to 0.1 g/mol, such as 0.05 g/mol to 0.5 g/mol, for example0.1 g/mol to 0.5 g/mol, such as 0.15 g/mol to 0.5 g/mol, for example 0.2g/mol to 0.5 g/mol, such as 0.25 g/mol to 0.5 g/mol, for example 0.3g/mol to 0.5 g/mol, such as 0.35 g/mol to 0.5 g/mol, for example 0.4g/mol to 0.5 g/mol, such as 0.45 g/mol to 0.5 g/mol, for example 0.05g/mol to 1.0 g/mol, such as 0.05 g/mol to 0.95 g/mol, for example 0.05g/mol to 0.9 g/mol, such as 0.05 g/mol to 0.85 g/mol, for example 0.05g/mol to 0.8 g/mol, such as 0.05 g/mol to 0.75 g/mol, for example 0.05g/mol to 0.7 g/mol, such as 0.05 g/mol to 0.65 g/mol, for example 0.05g/mol to 0.6 g/mol, such as 0.05 g/mol to 0.55 g/mol, for example 0.05g/mol to 0.5 g/mol, such as 0.05 g/mol to 0.45 g/mol, for example 0.05g/mol to 0.4 g/mol, such as 0.05 g/mol to 0.35 g/mol, for example 0.05g/mol to 0.3 g/mol, such as 0.05 g/mol to 0.25 g/mol, for example 0.05g/mol to 0.2 g/mol, such as 0.05 g/mol to 0.15 g/mol, for example 0.05g/mol to 0.1 g/mol, such as 0.1 g/mol to 1.0 g/mol, for example 0.15g/mol to 1.0 g/mol, such as 0.2 g/mol to 1.0 g/mol, for example 0.25g/mol to 1.0 g/mol, such as 0.3 g/mol to 1.0 g/mol, for example 0.35g/mol to 1.0 g/mol, such as 0.4 g/mol to 1.0 g/mol, for example 0.45g/mol to 1.0 g/mol, such as 0.5 g/mol to 1.0 g/mol, for example 0.55g/mol to 1.0 g/mol, such as 0.6 g/mol to 1.0 g/mol, for example 0.65g/mol to 1.0 g/mol, such as 0.7 g/mol to 1.0 g/mol, for example 0.75g/mol to 1.0 g/mol, such as 0.8 g/mol to 1.0 g/mol, for example 0.85g/mol to 1.0 g/mol, such as 0.9 g/mol to 1.0 g/mol, for example 0.95g/mol to 1.0 g/mol, such as 0.15 g/mol to 0.3 g/mol, for example 0.16g/mol to 0.3 g/mol, such as 0.17 g/mol to 0.3 g/mol, for example 0.18g/mol to 0.3 g/mol, such as 0.19 g/mol to 0.3 g/mol, for example 0.20g/mol to 0.3 g/mol, such as 0.21 g/mol to 0.3 g/mol, for example 0.22g/mol to 0.3 g/mol, such as 0.23 g/mol to 0.3 g/mol, for example 0.24g/mol to 0.3 g/mol, such as 0.25 g/mol to 0.3 g/mol, for example 0.26g/mol to 0.3 g/mol, such as 0.27 g/mol to 0.3 g/mol, for example 0.28g/mol to 0.3 g/mol, such as 0.29 g/mol to 0.3 g/mol, such as 0.15 g/molto 0.29 g/mol, such as 0.15 g/mol to 0.28 g/mol, such as 0.15 g/mol to0.27 g/mol, such as 0.15 g/mol to 0.26 g/mol, such as 0.15 g/mol to 0.25g/mol, such as 0.15 g/mol to 0.24 g/mol, such as 0.15 g/mol to 0.23g/mol, such as 0.15 g/mol to 0.22 g/mol, such as 0.15 g/mol to 0.21g/mol, such as 0.15 g/mol to 0.20 g/mol, such as 0.15 g/mol to 0.19g/mol, such as 0.15 g/mol to 0.18 g/mol, such as 0.15 g/mol to 0.17g/mol, such as 0.15 g/mol to 0.16 g/mol.

In one embodiment the aerogel typically has a density of 0.15 g/mol to0.30 g/mol.

The surface area of the aerogel is in one preferred embodiment in therange from 500 m²/g to 2000 m²/g such as from 500 m²/g to 1950 m²/g, forexample from 500 m²/g to 1900 m²/g, such as from 500 m²/g to 1850 m²/g,for example from 500 m²/g to 1800 m²/g, such as from 500 m²/g to 1750m²/g, for example from 500 m²/g to 1700 m²/g, such as from 500 m²/g to1650 m²/g, for example from 500 m²/g to 1600 m²/g, such as from 500 m²/gto 1550 m²/g, for example from 500 m²/g to 1500 m²/g, such as from 500m²/g to 1450 m²/g, for example from 500 m²/g to 1400 m²/g, such as from500 m²/g to 1350 m²/g, for example from 500 m²/g to 1300 m²/g, such asfrom 500 m²/g to 1250 m²/g, for example from 500 m²/g to 1200 m²/g, suchas from 500 m²/g to 1150 m²/g, for example from 500 m²/g to 1100 m²/g,such as from 500 m²/g to 1050 m²/g, for example from 500 m²/g to 1000m²/g, such as from 500 m²/g to 950 m²/g, for example from 500 m²/g to900 m²/g, such as from 500 m²/g to 850 m²/g, for example from 500 m²/gto 800 m²/g, such as from 500 m²/g to 750 m²/g, for example from 500m²/g to 700 m²/g, such as from 500 m²/g to 650 m²/g, for example from500 m²/g to 600 m²/g, such as from 500 m²/g to 550 m²/g, for examplefrom 500 m²/g to 2000 m²/g, such as from 550 m²/g to 2000 m²/g, forexample from 600 m²/g to 2000 m²/g, such as from 650 m²/g to 2000 m²/g,for example from 700 m²/g to 2000 m²/g, such as from 750 m²/g to 2000m²/g, for example from 800 m²/g to 2000 m²/g, such as from 850 m²/g to2000 m²/g, for example from 900 m²/g to 2000 m²/g, such as from 950 m²/gto 2000 m²/g, for example from 1000 m²/g to 2000 m²/g, such as from 1050m²/g to 2000 m²/g, for example from 1100 m²/g to 2000 m²/g, such as from1150 m²/g to 2000 m²/g, for example from 1200 m²/g to 2000 m²/g, such asfrom 1250 m²/g to 2000 m²/g, for example from 1300 m²/g to 2000 m²/g,such as from 1350 m²/g to 2000 m²/g, for example from 1400 m²/g to 2000m²/g, such as from 1450 m²/g to 2000 m²/g, for example from 1500 m²/g to2000 m²/g, such as from 1550 m²/g to 2000 m²/g, for example from 1600m²/g to 2000 m²/g, such as from 1650 m²/g to 2000 m²/g, for example from1700 m²/g to 2000 m²/g, such as from 1750 m²/g to 2000 m²/g, for examplefrom 1800 m²/g to 2000 m²/g, such as from 1850 m²/g to 2000 m²/g, forexample from 1900 m²/g to 2000 m²/g, such as from 1950 m²/g to 2000m²/g, for example from 800 m²/g to 1500 m²/g, such as from 850 m²/g to1500 m²/g, for example from 900 m²/g to 1500 m²/g, such as from 950 m²/gto 1500 m²/g, for example from 1000 m²/g to 1500 m²/g, such as from 1050m²/g to 1500 m²/g, for example from 1100 m²/g to 1500 m²/g, such as from1150 m²/g to 1500 m²/g, for example from 1200 m²/g to 1500 m²/g, such asfrom 1250 m²/g to 1500 m²/g, for example from 1300 m²/g to 1500 m²/g,such as from 1350 m²/g to 1500 m²/g, for example from 1400 m²/g to 1500m²/g, such as from 1450 m²/g to 1500 m²/g, for example from 800 m²/g to1450 m²/g, such as from 800 m²/g to 1400 m²/g, for example from 800 m²/gto 1350 m²/g, such as from 800 m²/g to 1300 m²/g, for example from 800m²/g to 1250 m²/g, such as from 800 m²/g to 1200 m²/g, for example from800 m²/g to 1150 m²/g, such as from 800 m²/g to 1100 m²/g, for examplefrom 800 m²/g to 1050 m²/g, such as from 800 m²/g to 1000 m²/g, forexample from 800 m²/g to 950 m²/g, such as from 800 m²/g to 900 m²/g,for example from 800 m²/g to 850 m²/g.

The surface area of the aerogel is in one preferred embodiment in therange from 800 to 1500 m²/g.

In one preferred embodiment the pore size of the aerogel is in the rangeof from 1 to 25 nm such as from 1 to 24 nm, for example from 1 to 22 nm,such as from 1 to 20 nm, for example from 1 to 18 nm, such as from 1 to16 nm, for example from 1 to 14 nm, such as from 1 to 12 nm, for examplefrom 1 to 10 nm, such as from 1 to 8 nm, for example from 1 to 6 nm,such as from 1 to 4 nm, for example from 1 to 2 nm, such as from 2 to 25nm, for example from 4 to 25 nm, such as from 6 to 25 nm, for examplefrom 8 to 25 nm, such as from 10 to 25 nm, for example from 12 to 25 nm,such as from 14 to 25 nm, for example from 16 to 25 nm, such as from 18to 25 nm, for example from 20 to 25 nm, such as from 22 to 25 nm, forexample from 24 to 25 nm, such as from 1 to 5 nm, for example from 5 to10 nm, such as from 10 to 15 nm, for example from 15 to 20 nm, such asfrom 20 to 25 nm, for example from 2 to 10 nm, such as from 2 to 9 nm,for example from 2 to 8 nm, such as from 2 to 7 nm, for example from 2to 6 nm, such as from 2 to 5 nm, for example from 2 to 4 nm, such asfrom 2 to 3 nm, for example from 3 to 10 nm, such as from 3 to 9 nm, forexample from 3 to 8 nm, such as from 3 to 7 nm, for example from 3 to 6nm, such as from 3 to 5 nm, for example from 3 to 4 nm, such as from 4to 10 nm, for example from 4 to 9 nm, such as from 4 to 8 nm, forexample from 4 to 7 nm, such as from 4 to 6 nm, for example from 4 to 5nm, such as from 5 to 9 nm, for example from 5 to 8 nm, such as from 5to 7 nm, for example from 5 to 6 nm, such as from 6 to 10 nm, forexample from 6 to 9 nm, such as from 6 to 8 nm, for example from 6 to 7nm, such as from 7 to 10 nm, for example from 7 to 9 nm, such as from 7to 8 nm, for example from 8 to 10 nm, such as from 8 to 9 nm, forexample from 9 to 10 nm.

The pore size of the aerogel is typically 2-5 nm.

The surface of the aerogels feel like a light but rigid foam, somethingbetween Styrofoam and the green floral foam used for arranging flowers.Aerogels are dry materials and do not resemble a gel in their physicalproperties but a nanofoam. Pressing softly on an aerogel typically doesnot leave a mark; pressing more firmly will leave a permanent dimple.Pressing firmly enough will cause a breakdown in the sparse structure,causing it to shatter like glass. Despite the fact that it is prone toshattering, it is very strong structurally. Its impressive load bearingabilities are due to the dendritic microstructure, in which sphericalparticles of average size 2-5 nm are fused together into clusters. Theseclusters form a three-dimensional highly porous structure of almostfractal chains, with pores smaller than 100 nm. The average size anddensity of the pores can be controlled during the manufacturing process.

Aerogels are remarkable thermal insulators because they almost nullifythree methods of heat transfer (convection, conduction, and radiation).They are good convective inhibitors because air cannot circulatethroughout the lattice. Silica aerogel is an especially good conductiveinsulator because silica is a poor conductor of heat—a metallic aerogel,on the other hand, would be a less effective insulator. Carbon aerogelis a good radiative insulator because carbon absorbs the infraredradiation that transfers heat.

Due to its hygroscopic nature, aerogel feels dry and acts as a strongdesiccant.

Aerogels appear semi-transparent because they, in one preferredembodiment, consist of up to 99% air. The color it does have is due toRayleight scattering of the shorter wavelengths of visible light by thenanosized dendritic structure. This causes it to appear bluish againstdark backgrounds and whitish against bright backgrounds.

Aerogels by themselves are hydrophilic, but chemical treatment can makethem hydrophobic. If they absorb moisture they usually suffer astructural change, such as contraction, and deteriorate, but degradationcan be prevented by making them hydrophobic. Aerogels with hydrophobicinteriors are less susceptible to degradation than aerogels with only anouter hydrophobic layer, even if a crack penetrates the surface.Hydrophobic treatment facilitates processing because it allows the useof a water jet cutter.

Aerogel can be used as drug delivery system due to its biocompatibility.Due to its high surface area and porous structure, drugs can be adsorbedfrom supercritical CO2. The release rate of the drugs can be tailoredbased on the properties of aerogel.

Alteration of the Surface Properties of Aerogels:

By means of functionalization, the surface properties of the aerogelaccording to the present invention can be altered; different functionalgroups can be used to change the properties of aerogel from hydrophilicto hydrophobic range. Controlling the surface coverage of the functionalgroup as well as its type is one of the goals of this study. Inprinciple, functionalization can be done by three basic methods:

-   -   1. Functionalization during the preparation of the gel        (sol-gel).    -   2. Liquid phase functionalization (by placing the wet gel in        functionalization solution).    -   3. Gas phase functionalization (by placing the aerogel in a gas        stream of functionalization solution).

By optimizing the working conditions of each method, it is possible tocontrol the functionalization degree of the desired functional group onthe aerogel surface, and as a result the loading as well as the releasetime of the active drug can be tailored.

The hydrophobicity of the aerogel can in one preferred embodiment beadjusted by use of monomers containing alkyl groups on some siliciumcompositions.

Bioactive Agents Encapsulated by Aerogels:

The present invention relates to encapsulation of one or more bioactiveagents into an aerogel. The one or more bioactive agents can be, but isnot limited to, the group consisting of proteins, peptides, enzymes,proteases, small organic or inorganic molecules, polysaccharides,pharmaceutical compositions or any combination thereof.

In one preferred embodiment one or more enzyme(s) are encapsulated intoone or more aerogel(s). In one embodiment encapsulation of one or moreenzymes into one or more aerogels results in stability of theenzyme—such as unaltered activity over time. In another embodiment theactivity of the enzyme is increased by encapsulation into the one ormore aerogel(s).

In one embodiment one or more protease(s) are encapsulated in theaerogel. Proteases are in general difficult to store in solution becausethey digest each other. When proteases on the other hand areencapsulated in an aerogel they are not in contact with each other.

The present invention also relates to encapsulation of one or moresubtilisins in the aerogel. Subtilisins comprises a family of serineproteases isolated from bacillus subtilis.

In another preferred embodiment the present invention relates toencapsulation of one or more hydrolytic enzymes. These hydrolyticenzymes comprises in one preferred embodiment hydrolytic enzymes thatdegrades polysaccharides and/or lipids. In yet another embodiment theaerogel encapsulates one or more oxidase(s). These oxidases can in oneembodiment result in production of hydrogenperoxide. The presentinvention also relates to incorporation of a combination of starchand/or amylase and one or more oxidase(s) for generation ofhydrogenperoxide.

In another embodiment the one or more enzymes are functionalized so itis actively incorporated into the three-dimensional structure of theaerogel. This leads to covalent attachment of the enzyme to thethree-dimensional structure of the aerogel.

In one preferred embodiment a mixture of more than one enzyme isencapsulated into the aerogel. In another embodiment one or more enzymesand one or more other bioactive agent(s) are encapsulated into the sameaerogel. In yet another embodiment more than one bioactive agent(s) areencapsulated into the same aerogel. In one preferred embodiment anenzyme and its substrate are encapsulated into the same aerogel.

In one preferred embodiment one or more bioactive agent(s) areencapsulated into an aerogel in a way so the one or more bioactiveagent(s) are located in individual compartments in the aerogel.

In one embodiment the one or more enzymes can be selected from the groupconsisting of hemicellulolytically active enzymes, amylolytically activeenzyme and/or cellulolytically active enzyme.

In another preferred embodiment the one or more bioactive agent(s)comprises endopeptidases.

In one embodiment the endopeptidase(s) comprises a Subtilisin (EC3.4.21.62). The Subtilisin (EC 3.4.21.62) has the followingcharacteristics: (i) optimum activity at a pH in the range of about7-10, and (ii) optimum activity at a temperature in the range of about55-65° C. The Subtilisin (EC 3.4.21.62) is in one embodiment Alcalase®.

In one embodiment the hemicellulolytically active enzyme(s) is selectedfrom the group consisting of Endo-1,4-beta-xylanase (E.C. 3.2.1.8),Xylan endo-1,3-beta-xylosidase (E.C. 3.2.1.32). Glucuronoarabinoxylanendo-1,4-beta-xylanase (E.C. 3.2.1.136), Beta-mannosidase (E.C.3.2.1.25), Mannan endo-1,4-beta-mannosidase (E.C. 3.2.1.78) and Mannanendo-1,6-beta-mannosidase (E.C. 3.2.1.101). In another preferredembodiment the hemicellulolytically active enzyme is a xylanase. In oneembodiment the xylanase is an endo-1,4-beta-xylanase (E.C. 3.2.1.8).

The amylolytically active enzyme(s) can in one preferred embodiment bean amylase. In another embodiment the one or more amylolytically activeenzyme(s) is selected from the group consisting of α- and β-amylases,amyloglucosidases (E.C. 3.2.1.3), pullulanases, α-1,6-endoglucanases,α-1,4-exoglucanases and isoamylases. The one or more amylolyticallyactive enzyme(s) can also be amyloglucosidase. In one preferredembodiment the amyloglucosidase is an 1,4-alpha-glucosidase.

In one embodiment the anti-fouling composition agent comprises one ormore aerogel(s) and at least one xylanase and at least oneamyloglucosidase.

In another embodiment the anti-fouling composition agent comprises oneor more aerogel(s) and at least one endo-1,4-beta-xylanase (E.C.3.2.1.8) and at least one 1,4-alpha-glucosidase (E.C. 3.2.1.3).

In one embodiment The anti-fouling composition comprising one or moreaerogel(s) and from about 0.1-10% of bioactive agent(s) by weight. Inanother preferred embodiment the anti-fouling composition comprising oneor more aerogel(s) and from about 0.2-5% of bioactive agent(s) byweight. In yet another preferred embodiment the anti-fouling compositioncomprising one or more aerogel(s) and from about 0.5-1% of bioactiveagent(s) by weight.

One or more bioactive agents can be encapsulated into the one or moreaerogels. When two bioactive agents are encapsulated the presentinvention relates in one embodiment to the combinations illustrated intable 1 and 2.

TABLE 1 combination of bioactive agents for encapsulation into one ormore aerogels. Small organic Small inorganic Pharmaceutical ProteinsPeptides Enzymes Proteases molecules molecules Polysaccharidescompositions Proteins X X X X X X X X Peptides X X X X X X X X Enzymes XX X X X X X X Proteases X X X X X X X X Small organic X X X X X X X Xmolecules Small inorganic X X X X X X X X molecules Polysaccharides X XX X X X X X Pharmaceutical X X X X X X X X compositions

TABLE 2 combination of bioactive agents for encapsulation into one ormore aerogels. Hydrolytic Hemicellulytically AmylolyticallyCellulytically Oxidases Endopeptidases Proteases Subtilisins enzymesactive enzymes active enzymes active enzymes Oxidases X X X X X X X XEndopeptidases X X X X X X X X Proteases X X X X X X X X Subtilisins X XX X X X X X Hydrolytic X X X X X X X X enzymes Hemicellulytically X X XX X X X X active enzymes Amylolytically X X X X X X X X active enzymesCellulytically X X X X X X X X active enzymes

In one embodiment two bioactive agents of the same type can be combined.

Antifouling Species Generated by Oxidase Enzymes

The composition according to the present invention preferably comprisesat least one enzyme. In one embodiment the enzyme is an oxidase capableof acting on a compound, such as a substrate for said oxidase, whereinsaid action results in the formation of an antifouling species includingan antimicrobial species comprising an antimicrobial activity, andwherein said compound does not form part of said coating composition.

In a more preferred embodiment the enzyme is an oxidase the activity ofwhich results in the formation of a peroxide.

The oxidase can be present in said coating composition in combinationwith one or more additional enzymes including, but not limited to, anesterase, including a lipase, an amidase, including a protease, and apolysaccharide degrading enzyme, wherein said one or more additionalenzyme(s), alone or in any combination, can be included in the presenceor absence of one or more substrates for one or more of said enzymes.

The antifouling species comprising an antifouling activity is preferablygenerated when the at least one enzyme acts on a compound, or aprecursor thereof including a polymer, capable of being secreted by amicrobial organism. The compound can be a degradation product of aprecursor compound, including a polymer secreted by and/or located onthe surface of microbial organisms, wherein said degradation product isprovided by a precursor enzyme acting on said precursor compound.

Further Antifouling Species and Enzymes Resulting in their Production

The species of the invention having antifoulant or antimicrobialactivity can be any species capable of being produced e.g. as the resultof an enzyme-substrate reaction. As such, there can be mentioned manyspecies having antifouling activity, species havingantibacterial/antifungal activity, species having biocidal activity, andspecies having biorepellent activity.

In one preferred embodiment the one or more aerogel(s) comprises one ormore enzymes and one or more biocides.

The species having antimicrobial activity is thus produced by anenzymatic reaction between an enzyme and a substrate in the form of acompound which is preferably secreted by a microbial organism. Specieshaving antimicrobial activity can be any species obtained as the directresult of enzymatic reaction between the enzyme and the compound, aswell as any species formed from the product of such enzymatic reactionthrough further enzymatic and/or chemical reaction.

The compounds are not limited to microbial secretion products. Thecompounds of the invention can be any non-toxic compound supplied to apredetermined environment, such as a dock harbouring a ship hull, andcapable of being converted into an antifouling species, including anantimicrobial species by the action of the at least one enzyme,including an oxidase.

Furthermore, it is also envisaged that antifouling species, including anantimicrobial species can be generated by a combination of i) enzymaticaction on secreted microbial products, including polymers anddegradation products thereof, and ii) enzymatic action on exogenouslyadded compounds or precursor compounds, wherein said combination ofenzymatic actions results in the formation of one or more antifoulingspecies, including an antimicrobial species having an antimicrobialactivity.

In accordance with the invention, the at least one enzyme, preferably anoxidase the activity of which results in the production of peroxide,including hydrogenperoxide, is comprised in the coating compositionaccording to the invention in an effective amount to reduce or preventfouling of a surface coated with the composition. In the present contextthe term “an effective amount” means an amount which is sufficient tocontrol or eliminate or reduce or at least substantially reduce thesettling of microbial organisms, plants and/or animals, includingaquatic organisms such as bacteria, protozoa, algae and invertebrates,on a surface coated with the composition according to invention.

In order to test the amount of the at least one enzyme required in orderto sufficiently reduce or prevent fouling, any type of standard ormodified antifouling bioassay can be applied, including settlementassays as described by Willemsen (1994). In one presently preferredembodiment, the amount of the enzyme is in the range of from about 0.1to preferably less than 10% (w/w) coating composition (dry weight), suchas from about 0.1 to less than 9% (w/w), for example from about 0.1 toless than 8% (w/w), such as from about 0.1 to less than 7% (w/w), forexample from about 0.1 to less than 6% (w/w), such as from about 0.1 toless than 5.5% (w/w), for example from about 0.1 to less than 5.0%(w/w), such as from about 0.1 to less than 4.5% (w/w), for example fromabout 0.1 to less than 4.0% (w/w), such as from about 0.1 to less than3.5% (w/w), for example from about 0.1 to less than 3.0% (w/w), such asfrom about 0.1 to less than 2.5% (w/w), for example from about 0.1 toless than about 2.0% (w/w), such as from about 0.1 to less than about1.5% (w/w), for example from about 0.1 to less than about 1.0% (w/w),such as from about 0.1 to less than about 0.5% (w/w).

In another embodiment the amount of the enzyme is present in the coatingcomposition in the range of from about 0.2% (w/w) to about 0.4% (w/w)coating composition (dry weight), such as from about 0.4% (w/w) to about0.6% (w/w), for example from about 0.6% (w/w) to about 0.8% (w/w)coating composition, such as from about 0.8% (w/w) to about 1.0% (w/w),for example from about 1.0% (w/w) to about 1.2% (w/w) coatingcomposition, such as from about 1.2% (w/w) to about 1.4% (w/w), forexample from about 1.4% (w/w) to about 1.6% (w/w) coating composition,such as from about 1.6% (w/w) to about 1.8% (w/w), for example fromabout 1.8% (w/w) to about 2.0% (w/w) coating composition, such as fromabout 2.0% (w/w) to about 2.5% (w/w), for example from about 2.5% (w/w)to about 3.0% (w/w) coating composition, such as from about 3.0% (w/w)to about 3.5% (w/w), for example from about 3.5% (w/w) to about 4.0%(w/w) coating composition, such as from about 4.0% (w/w) to about 4.5%(w/w), for example from about 4.5% (w/w) to about 5.0% (w/w) coatingcomposition.

In a preferred embodiment the at least one enzyme is an oxidase theactivity of which results in the formation of a peroxide, includinghydrogen peroxide. The amount of hydrogen peroxide generated inaccordance with the present invention depends on the amount of availablecompound on which the at least one oxidase can act. It will be possibleto determine the amount of hydrogen peroxide generated by using themethod of Janssen and Ruelius disclosed in Biochem. Biophys. Acta(1968), vol. 151, pages 330-342.

The amount of hydrogen peroxide generated is in preferred embodimentsabout or at least about 1 nmol/cm²/day, such as 2 nmol/cm²/day, forexample 3 nmol/cm²/day, such as 4 nmol/cm²/day, for example 5nmol/cm²/day, such as 2 nmol/cm²/day, for example 3 nmol/cm²/day, suchas 4 nmol/cm²/day, for example 5 nmol/cm²/day, such as 6 nmol/cm²/day,for example 7 nmol/cm²/day, such as 8 nmol/cm²/day, for example 9nmol/cm²/day, such as 10 nmol/cm²/day, for example 12 nmol/cm²/day, suchas 14 nmol/cm²/day, for example 16 nmol/cm²/day, such as 18nmol/cm²/day, for example 20 nmol/cm²/day, such as 22 nmol/cm²/day, forexample 24 nmol/cm²/day, such as 26 nmol/cm²/day, for example 28nmol/cm²/day, such as 30 nmol/cm²/day, for example 32 nmol/cm²/day, suchas 34 nmol/cm²/day, for example 36 nmol/cm²/day, such as 38nmol/cm²/day, for example 40 nmol/cm²/day, such as 42 nmol/cm²/day, forexample 44 nmol/cm²/day, such as 46 nmol/cm²/day, for example 48nmol/cm²/day, such as 50 nmol/cm²/day, for example 55 nmol/cm²/day, suchas 60 nmol/cm²/day, for example 65 nmol/cm²/day, such as 70nmol/cm²/day, for example 75 nmol/cm²/day, such as 80 nmol/cm²/day, forexample 85 nmol/cm²/day, such as 90 nmol/cm²/day, for example 95nmol/cm²/day, such as 100 nmol/cm²/day, for example 110 nmol/cm²/day,such as 120 nmol/cm²/day, for example 130 nmol/cm²/day, such as 140nmol/cm²/day, for example 150 nmol/cm²/day, such as 160 nmol/cm²/day,for example 170 nmol/cm²/day, such as 180 nmol/cm²/day, for example 190nmol/cm²/day, such as 200 nmol/cm²/day, for example 220 nmol/cm²/day,such as 240 nmol/cm²/day, for example 260 nmol/cm²/day, such as 280nmol/cm²/day, for example 300 nmol/cm²/day, such as 320 nmol/cm²/day,for example 340 nmol/cm²/day, such as 360 nmol/cm²/day, for example 380nmol/cm²/day, such as 400 nmol/cm²/day, for example 420 nmol/cm²/day,such as 440 nmol/cm²/day, for example 460 nmol/cm²/day, such as 480nmol/cm²/day, for example 500 nmol/cm²/day, such as 520 nmol/cm²/day,for example 540 nmol/cm²/day, such as 560 nmol/cm²/day, for example 580nmol/cm²/day, such as 600 nmol/cm²/day, for example 620 nmol/cm²/day,such as 640 nmol/cm²/day, for example 660 nmol/cm²/day, such as 680nmol/cm²/day, for example 700 nmol/cm²/day, such as 720 nmol/cm²/day,for example 740 nmol/cm²/day, such as 760 nmol/cm²/day, for example 780nmol/cm²/day, such as 800 nmol/cm²/day, for example 820 nmol/cm²/day,such as 840 nmol/cm²/day, for example 860 nmol/cm²/day, such as 880nmol/cm²/day, for example 900 nmol/cm²/day, such as 920 nmol/cm²/day,for example 940 nmol/cm²/day, such as 960 nmol/cm²/day, for example 980nmol/cm²/day, such as 1000 nmol/cm²/day.

Preferred oxidases include, but is not limited to, malate oxidase;glucose oxidase; hexose oxidase; cholesterol oxidase; arylalcoholoxidase: galactose oxidase; alcohol oxidase; lathosterol oxidase;aspartate oxidase; L-amino-acid oxidase; D-amino-acid oxidase; amineoxidase; D-glutamate oxidase; ethanolamine oxidase; NADH oxidase; urateoxidase (uricase); superoxide dismutase; and the like.

In one preferred embodiment the at least one enzyme is a hexose oxidase,including, but not limited to any oxidoreductase of class EC 1.1.3.5.Hexose oxidases are enzymes which in the presence of oxygen is capableof oxidising D-glucose and several other reducing sugars includingmaltose, lactose and cellobiose to their corresponding lactones withsubsequent hydrolysis to the respective aldobionic acids. Hexose oxidasediffers from another oxidoreductase, glucose oxidase, which can onlyconvert D-glucose, in that the enzyme can utilise a broader range ofsugar substrates.

Hexose oxidase is produced naturally by several marine algal species.Such species are found inter alia in the family Gigartinaceae. In onepreferred embodiment the hexose oxidase is obtained from the marinealgae Chondrus cripus. Reference is made to EP 0 832 245. WO 96/40935and WO 98/13478 also disclose the cloning and expression in recombinanthost organisms of a gene encoding a protein with HOX activity.

In another preferred embodiment the compound and the enzyme,respectively, is selected from glucose/hexose oxidase; glucose/glucoseoxidase; L amino acid/L amino acid oxidase; galactose/galactose oxidase;lactose/beta-galacto sidase/hexose oxidase; 2-deoxyglucose/glucoseoxidase; pyranose/pyranose oxidase; and mixtures thereof.

Precursor Enzymes

The antifouling species, including an antimicrobial species can begenerated directly by the action of the at least one enzyme, optionallyin combination with an initial action of one or more precursor enzymes.In the latter case, the precursor enzyme(s) and the precursorcompound(s) are selected such that the precursor enzyme(s) eventuallygenerates the compound.

An example of a precursor enzyme is any polysaccharide digesting enzyme,including amyloglucosidase, and an example of a precursor compound isany polysaccharide.

Thus in one embodiment the coating composition can comprise at least oneoxidase such as e.g. hexose oxidase and at least one amylolyticallyactive enzyme, such as e.g. an amyloglucosidase, and/or at least onehemicellulolytically active enzyme, such as e.g. a xylanase, and/or atleast one cellulolytically active enzyme, such as e.g. a cellulase,including any combination of an oxidase with the aforementionedpolysaccharide degrading enzymes, such as an oxidase and anamylolytically active enzyme, an oxidase and a hemicellulolyticallyactive enzyme, an oxidase and a cellulolytically active enzyme, anoxidase and an amylolytically active enzyme and a hemicellulolyticallyactive enzyme, such as an oxidase and an amylolytically active enzymeand a cellulolytically active enzyme, and an oxidase and ahemicellulolytically active enzyme and an cellulolytically activeenzyme.

A number of other enzymes, as alternatives to an oxidase, or in additionto oxidases, can be employed in accordance with the present invention,either alone or in any combination, including a combination wherein theat least one oxidase is also present.

Esterases and Lipases

Esterases and lipases are triacylglycerol hydrolysing enzymes capable ofsplitting of fatty acids having short, medium and long chain lengths.Esterases and lipases degrade cell wall lipids and other lipidassociated macromolecules at the surface of microbial organisms.

Accordingly, in one embodiment the at least one enzyme is an esteraseand the compound is an ester bond-containing species. Examples ofesterases include, but is not limited to, carboxylesterase,arylesterase, acetylesterase, and the like.

In yet another embodiment the at least one enzyme/precursor enzyme is alipase such as, but not limited to, triacylglycerol lipase, lipoproteinlipase, and the like.

Proteases

Proteinaceous materials involved in fouling the surfaces are subject todisruption by proteases. Families of proteolytic enzymes are well known,as reviewed in Neurath, Science 224, 350-357, 1984. Candidates for usein non-toxic anti-fouling coating compositions can be drawn from thesefamilies, trypsin and subtilisn being an example of serine proteases oftype I and II, papain being an example of a sulfhydryl protease, pepsinbeing an example of an acid protease, carboxypeptidase A and B andthermolysin being examples of metalloproteases of type I and II. Otherprotease families of relevance are the aminopeptidases, the collagenasesand the calcium and ATP-activated proteases, each with numerousexamples.

Accordingly, in a still further embodiment the at least oneenzyme/precursor enzyme is a protease such as, but not limited to,subtilisins, chymotrypsins, trypsins, elastases, cathepsins, papains,chromopapains, pepsins, carboxypeptidase A, carboxypeptidase B,thermolysins, calcium activated proteases, ATP-activated proteases,exopeptidases such as aminopeptidases and carboxypeptidases,endopeptidases, and the like.

One class of preferred enzymes are the subtilisins. Subtilisins areserine endopeptidases. Examples include subtilisin BPN′ (also known assubtilisin B, subtilopeptidase B, subtilopeptidase C, Nagarse, Nagarseproteinase, subtilisin Novo, bacterial proteinase Novo) and subtilisinCarlsberg (subtilisin A, subtilopeptidase A, alcalase Novo). Now groupedunder IUBMB enzyme nomenclature EC 3.4.21.62, formerly EC 3.4.4.16 andincluded in EC 3.4.21.14. Subtilisin enzymes are produced by variousBacillus subtilis strains and other Bacillus species.

Further examples of subtilisins include, but is not limited to, e.g.alcalase; alcalase 0.6 L; alcalase 2.5 L; ALK-enzyme; bacillopeptidaseA; bacillopeptidase B; Bacillus subtilis alkaline proteinase bioprase;bioprase AL 15; bioprase APL 30; colistinase; (see also comments);subtilisin J; subtilisin S41; subtilisin Sendai; subtilisin GX;subtilisin E; subtilisin BL; genenase I; esperase; maxatase; alcalase;thermoase PC 10; protease XXVII; thermoase; superase; subtilisin DY;subtilopeptidase; SP 266; savinase 8.0 L; savinase 4.0T; kazusase;protease VIII; opticlean; Bacillus subtilis alkaline proteinase; proteinA 3 L; savinase; savinase 16.0 L; savinase 32.0 L EX; orientase 10B;protease S.

Accordingly, one particularly preferred protease is endopeptidases ofthe subtilisin type (EC 3.4.21.62). Subtilisin type proteases can beapplied in the form of a commercially available enzyme preparations suchas Alcalase®. Alcalase® is a serine-type protease characterised by agood performance at elevated temperatures and moderate alkalinity. In apresently preferred embodiment the enzyme preparation Alcalase 2.5 L,Type DX® is applied. However it is also contemplated that otherAlcalase® products, including Alcalase 2.0 T®, Alcalase 3.0 T® andAlcalase 2.5 L, Type DX®, can be applied in accordance with the presentinvention. Such Alcalase® enzyme preparations are available fromNovozymes (Novozymes, Novo Alle, 2880 Bagsvaerd, Denmark).

However, it is also within the scope of the invention that otherproteases having essentially the same characteristics as the protease ofAlcalase® can be successfully applied in accordance with the invention.Thus, it is contemplated that other proteases, such as subtilisins,having essentially the same temperature and pH profiles as the Alcalase,can be utilised. The temperature and pH profiles of the Alcalase can befound on the product sheet from Novozyme A/S (B259f-GB).

Accordingly, it is within the scope of the invention that a subtilisintype protease (EC 3.4.21.62) having the following characteristics: (i)optimum activity at a pH in the range of about 7 to 10, such as frommore than 7.5 to about 10; and (ii) optimum activity at a temperature inthe range of from about or more than 55 to about 65° C., mayadvantageously be applied.

Polysaccharide Degrading Enzymes

Enzymes/precursor enzymes capable of degrading polysaccharides aregenerally desirable in combination with an oxidase the activity of whichresults in the production of peroxide. The reason is that polysaccharidedigesting enzymes can break down a polysaccharide component of amicrobial adhesive structure and/or degrade important structuralpolysaccharides of microorganisms into building blocks of preferablymono- and/or disaccharides. Such compounds and precursors thereof aresubstrates for oxidases and their formation thus enhances the subsequentproduction of peroxides. Additionally, the polysaccharide digestingenzymes of the present invention can prevent or interfere with theattachment process or the subsequent growth, metamorphosis orreplication of the fouling organisms in question.

Accordingly, in a still further embodiment the at least oneenzyme/precursor enzyme is a polysaccharide digesting enzyme, such as,but not limited to, alpha-amylase, beta-amylase, beta-glucosidase,glucosidase, glycosidase, cellulase, pectinase, hyaluonidase,beta-glucuronidase.

The enzymes beta-amylase, beta-glucosidase, and glycosidase all belongto the group of enzymes that can degrade polysaccharides. Pectinase andcellulase are enzymes which break down pectin and cellulose,respectively, two ubiquitous structural polymers of the plant cell walland cell wall connective tissue matrix. Lysozyme and achromopeptidasecan also break cell walls, the latter having an exceptional range ofactivity against microorganisms. Hyaluronic acid and collagen haveanalogous structural roles in animals and are degraded by hyaluronidaseand collagenase, respectively. Beta-Glucuronidase will also break downhyaluronic acid.

Additionally preferred polysaccharide degrading enzymes are“hemicellulolytically active” enzymes, “cellulolytically active”enzymes, and “amylolytically active” enzymes. The first group belongenzymes such as xylanases, which have the capability to degrade at leastone substance belonging to the group of compounds and precursorcompounds generally referred to as hemicellulose, including xylans andmannans, such as Endo-1,4-beta-xylanase (E.C. 3.2.1.8), Xylanendo-1,3-beta-xylosidase (E.C. 3.2.1.32), Glucuronoarabinoxylanendo-1,4-beta-xylanase (E.C. 3.2.1.136), Beta-mannosidase (E.C.3.2.1.25), Mannan endo-1,4-beta-mannosidase (E.C. 3.2.1.78) and Mannanendo-1,6-beta-mannosidase (E.C. 3.2.1.101).

Enzymes having “cellulolytic activity” are also generally referred to ascellulases and is used herein to designate any cellulose hydrolysingenzyme.

“Amylolytically active” enzymes includes, in the present context,amylases, such as α-amylases and β-amylases, amyloglucosidases,pullulanases, α-1,6-endoglucanases, α-1,4-exoglucanases and isoamylases.

The above-mentioned enzymes occur in preferred embodiments incombination with at least one oxidase. Accordingly, when the coatingcomposition e.g. comprises an aerogel which comprises an oxidase capableof acting on a compound, wherein said action results in the formation ofan antimicrobial species, the aerogel and/or coating composition can infurther embodiments comprise one or more of

at least one esterase from the above group, optionally in the absence ofa substrate for said esterase, and/or

at least one lipase from the above group, optionally in the absence of asubstrate for said lipase, and/or

at least one protease from the above group, optionally in the absence ofa substrate for said protease, and/or

at least one polysaccharide degrading enzyme from the above group,optionally in the absence of a substrate for said enzyme.

Preferred combinations of the above enzymes in combination with the atleast one oxidase include

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one hydrolytic enzyme,optionally in the absence of a substrate for such a hydrolytic enzyme,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one esterase,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one lipase,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one protease,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one polysaccharide digestingenzyme,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one esterase and at least onelipase,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one esterase and at least oneprotease,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one esterase and at least onepolysaccharide digesting enzyme,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one esterase and at least onelipase and at least one protease,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one esterase and at least onelipase and at least one polysaccharide digesting enzyme,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one esterase and at least onelipase and at least one protease and at least one polysaccharidedigesting enzyme,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one lipase and at least oneprotease,

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one lipase and at least oneprotease and at least one polysaccharide digesting enzyme, and

a coating composition comprising at least one oxidase in the absence ofa substrate for said oxidase and at least one protease and at least onepolysaccharide digesting enzyme.

Accordingly, it will be understood that the substrate for the one ormore enzymes can be present or not present in the coating compositionand/or the aerogel.

In various embodiments, the above coating compositions comprising anaerogel do not comprise a substrate for the one or more enzyme(s) and/orthe one or more precursor enzyme(s) employed. Accordingly, there areprovided embodiments wherein any one of the above-mentioned coatingcompositions i) does not comprise any substrate for the at least oneesterase, when an esterase is present, ii) does not comprise anysubstrate for the at least one lipase, when a lipase is present, iii)does not comprise any substrate for the at least one protease, when aprotease is present, and iv) does not comprise any substrate for the atleast one polysaccharide digesting enzyme, when a polysaccharidedigesting enzyme is present, v) does not comprise the substrate for theprecursor enzyme.

In further embodiments the above coating compositions according to theinvention i) do not comprise a substrate for an esterase and a lipase,when at least an esterase and a lipase are present, optionally incombination with further enzymes ii) do not comprise a substrate for anesterase and a protease, when at least an esterase and a protease arepresent, optionally in combination with further enzymes, iii) do notcomprise a substrate for an esterase and a polysaccharide digestingenzyme, when at least an esterase and a polysaccharide digesting enzymeare present, optionally in combination with further enzymes, iv) do notcomprise a substrate for an lipase and a protease, when at least alipase and a protease are present, optionally in combination withfurther enzymes, v) do not comprise a substrate for a lipase and apolysaccharide digesting enzyme, when at least a lipase and apolysaccharide digesting enzyme are present, optionally in combinationwith further enzymes, and vi) do not comprise a substrate for a proteaseand a polysaccharide digesting enzyme, when at least a protease and apolysaccharide digesting enzyme are present, optionally in combinationwith further enzymes.

In the present invention, the at least one enzyme comprised in thecoating composition can be any one or more of a purified enzyme or acrude enzyme. The source of the enzyme includes microorganisms, plants,and animals. When incorporating an enzyme into the coating composition,the enzyme may be directly incorporated or it can be used aftermodification with another species, or in the form of an immobilizedenzyme. Immobilization includes enzymes entrapped in reverse micelles;enzymes modified with lipids or surfactants; enzymes modified withpolyethylene glycol; and enzymes immobilized on polymer matrices, amongother forms.

Rosins

It is in one embodiment preferred to include into a coating compositionof the invention at least one rosin. Rosins are solid materials thate.g. occur naturally in the oleo rosin of pine trees and is typicallyderived from the oleo resinous exudate of the living tree, from agedstumps and from tall oil produced as a by-product of kraft papermanufacture.

Rosin compounds have a number of highly desirable properties for use asbinders in antifouling paints such as e.g. being fairly non-toxic tohumans, being compatible with a large number of other binders and beingrelatively inexpensive and readily available from natural resources.

Thus, rosins are used in paints as binders, and thereby provide a rathernon-toxic alternative to synthetic and more toxic binders such as e.g.polymeric binder components as epoxy, polyvinylacetate,polyvinylbutyrate and polyvinylchloride acetate.

Rosin is typically classed as gum rosin, wood rosin, or as tall oilrosin which indicates its source. The rosin materials can be usedunmodified, in the form of esters of polyhydric alcohols, in the form ofrosins polymerised through the inherent unsaturation of the molecules orin the form of hydrogenated rosin. Thus, rosin can be further treated bye.g. hydrogenation, dehydrogenation, polymerisation, esterification, andother post treatment processes. Additionally, rosin with e.g. freecarboxylic acid groups are capable of reacting with metals and therebyforming rosin metal salts.

Accordingly, the rosin compound of the antifouling paint composition ofthe present invention is at least one selected from rosins, rosinderivatives, and rosin metal salts. Examples of rosins include tallrosin, gum rosin, and wood rosin. Examples of rosin derivatives includehydrogenated rosins, modified rosins obtained by reacting rosins withmaleic anhydride, formylated rosins, and polymerised rosins. Examples ofrosin metal salts include zinc rosinates, calcium rosinates, copperrosinates, magnesium rosinates, and products of the reaction of rosinswith compounds of other metals.

Rosins of natural origin have the beneficial effect that when used incombination with enzymes, the activity of said enzymes are notsubstantially affected by the rosins as compared to enzymes in paintcompositions prepared with synthetic binders of non-natural origin.Accordingly, it was found that no enzyme activity was present in paintcompositions comprising protease and synthetic binders of non-naturalorigin.

The rosins are furthermore believed to have an immobilising effect onthe enzymes and thus preventing the enzymes from being released from thepaint composition into the environment.

The composition according to invention comprises a rosin compoundwherein the content of the rosin compound is in the range of from about5 to about 60% by weight. It is preferred that the amount of rosincompound is higher than about 10% such as up to about 20% by weight.However, it is also contemplated that the amount of rosin compound inthe composition can be up to about 30%, such as up to about 40%, up toabout 50% and up to about 55%. Thus, a pigmented composition accordingto the invention could advantageously comprise an amount of rosincompound in the range of about 10-30% by weight, and a lacquercomposition could comprise up to about 60% of rosin compound by weight.

Resins

As an alternative to rosin compounds, any suitable resin compound can beemployed, such as the resins described below.

The resin produced by most plants is a viscous liquid, typicallycomposed mainly of volatile fluid terpenes, with lesser components ofdissolved non-volatile solids which make resin thick and sticky. Themost common terpenes in resin are the bicyclic terpenes alpha-pinene,beta-pinene, delta-3 carene and sabinene, the monocyclic terpeneslimonene and terpinolene, and smaller amounts of the tricyclicsesquiterpenes longifolene, caryophyllene and delta-cadinene. Someresins also contain a high proportion of resin acids. The individualcomponents of resin can be separated by fractional distillation

A few plants produce resins with different compositions, most notablyJeffrey Pine and Gray Pine, the volatile components of which are largelypure n-heptane with little or no terpenes. The exceptional purity of then-heptane distilled from Jeffrey Pine resin, unmixed with other isomersof heptane, led to its being used as the defining zero point on theoctane rating scale of petrol quality. Because heptane is highlyflammable, distillation of resins containing it is very dangerous. Someresin distilleries in California exploded because they mistook JeffreyPine for the similar but terpene-producing Ponderosa Pine.

Some resins when soft are known as oleo-resins, and when containingbenzoic acid or cinnamic acid they are called balsams. Other resinousproducts in their natural condition are a mix with gum or mucilaginoussubstances and known as gum resins. Many compound resins have distinctand characteristic odors, from their admixture with essential oils.

Certain resins are obtained in a fossilized condition, amber being themost notable instance of this class; African copal and the kauri gum ofNew Zealand are also procured in a semi-fossil condition.

Solidified resin from which the volatile terpene components have beenremoved by distillation is known as rosin. Typical rosin is atransparent or translucent mass, with a vitreous fracture and a faintlyyellow or brown colour, non-odorous or having only a slight turpentineodour and taste.

1) It is insoluble in water, mostly soluble in alcohol, essential oils,ether and hot fatty oils, 2) softens and melts under the influence ofheat, is not capable of sublimation, and burns with a bright but smokyflame.

This comprises a complex mixture of different substances includingorganic acids named the resin acids. These are closely related to theterpenes, and derive from them through partial oxidation. Resin acidscan be dissolved in alkalis to form resin soaps, from which the purifiedresin acids are regenerated by treatment with acids. Examples of resinacids are abietic acid (sylvic acid), C₂₀H₃₀O₂, plicatic acid containedin cedar, and pimaric acid, C₂₀H₃₅O₂, a constituent of gallipot resin.Abietic acid can also be extracted from rosin by means of hot alcohol;it crystallizes in leaflets, and on oxidation yields trimellitic acid,isophthalic acid and terebic acid. Pimaric acid closely resemblesabietic acid into which it passes when distilled in a vacuum; it hasbeen supposed to consist of three isomers.

Synthetic resins are materials with similar properties to naturalresins—viscous liquids capable of hardening. They are typicallymanufactured by esterification or soaping of organic compounds. Theclassic variety is epoxy resin, manufactured through polymerization-polyaddition or polycondensation reactions, used as a thermoset polymer foradhesives and composites. One more category, which constitutes 75% ofresins used, is unsaturated polyester resin. Ion exchange resin isanother important class with application in water purification andcatalysis of organic reactions. Other examples of resin includes AT-10Resin and melamine resin.

Repellents

In addition to the at least one enzyme capable of producing anantifouling species, including an antimicrobial species and means forimmobilization thereof, including rosins, as described above, thecoating composition of the invention can also comprise additional agentsuseful for preventing fouling, particularly macrofouling. One such groupof agents is termed repellents of the macrofouling organisms. Repellentsbelong to a group of biologically active compounds which repel ratherthan attract microbial organisms.

Repellents according to the invention include molecules that arecustomarily associated with some inimicable material formed by apredator (or other non-compatible organism) of the macrofoulingorganism. An example is the material customarily excreted by starfishthat causes such prey organism as scallops to immediately react to thematerial and try to escape therefrom. When affixed to a surface asdescribed herein, the repellent would not freely diffuse but would actto elicit the escape response when the organism contacted the surfacebeing protected. An example of this would be a purified chemicalrepellent or an impure suspension containing the active chemicalrepellent that is obtained by grinding and partially fractionating acoral or algae preparation. The repellents of choice are those naturalproducts used by corals, seaweeds and other aquatic organisms to avoidfouling of their surfaces.

Surfactants

In addition to natural products that can act as repellents, the surfaceprotection can also be brought about by affixing a surfactant. Somerepellents will be surfactants and vice versa, but as surfactants aregenerally not regarded as repellents in all senses of the word, they areconsidered as a separate class of bioactive agents having a usefuleffect in combination with enzymes and/or repellents of this invention.

A surfactant can have an inhibitory effect on attachment of organisms toa surface even when immobilized on or within a coating composition ofthe invention. Specific examples of immobilized surfactants arecationic, anionic and non-ionic surfactants such as quaternary ammoniumions, dipalmitoyl phosphatidyl choline, aralkyl sulfonates and sucroseesters, respectively. Other examples are set forth in the Kirk-OthmerEncyclopedia of Chemical Technology, Vol. 22, pages 332-432, John Wiley& Sons, New York, 1983.

Tannic Acids

Yet another example of a compound capable of being incorporated intocoating compositions according to the invention is tannic acid, arepresentative compound of the tannins, a family of compounds secretedby certain species of marine brown algae (e.g. Sargassum), which appearto restrict bacterial colonization of the frond surface (Sieburth andConover (1965) Nature 208 52). This is exemplary of the class ofcompounds, useful in non-toxic anti-fouling coatings, that act byinterference with enzymatic reactions necessary for attachment of macro-or micro-organisms. Candidate compounds in this category include kojicacid and similar inhibitors of polyphenol oxidase. These inhibitors willinterfere with the cross-linking of cement-forming materials. of similarvalue are glucosyl transferase inhibitors which will prevent theformation of polysaccharide adhesives used in adhesion, mutastein,ribocitrin, 1-deoxynojirimycin, acarbose, and N-methyldeoxynojirimycinbeing exemplary of these.

Function of Encapsulation

In one preferred embodiment one or more bioactive agent(s) areencapsulated into an aerogel to stabilize the one or more bioactiveagent(s).

In one preferred embodiment one or more bioactive agent(s) areencapsulated into an aerogel to retain or improve the activity of theone or more bioactive agent(s).

In one preferred embodiment one or more bioactive agent(s) areencapsulated into an aerogel to retain or improve the heat stability ofthe one or more bioactive agent(s).

Degradation of Aerogels

Aerogels are degraded over time. Aerogels comprises a self-polishingeffect. The one or more encapsulated bioactive agents will be exposed tothe surface over time. In one embodiment the one or more encapsulatedbioactive agents will be released from the one or more aerogel(s) bycontrolled release.

In one embodiment hydrolysis of the hydrolysable moieties of the coatingcomposition generates a self-polishing effect. Being submerged in waterthe hydrolysable moieties will slowly hydrolyse at the interface betweenthe coating composition and the water phase. When sufficient hydrophilicgroups have been formed, the coating composition becomes water-solubleand dissolves leading to a “self-polishing” effect.

In one preferred embodiment the self-polishing effect comprises a trueself-polishing effect. In another embodiment the self-polishing effectcomprises a simple self-polishing effect

The leaching of the one or more encapsulated bioactive agent(s) is slowor absent when the aerogel is exposed to water or another liquid overperiods of hours. The leaching will be 0 to 2% per hour at 37° C.calculated based on total encapsulated protein.

The leaching of the one or more encapsulated bioactive agent(s) from theaerogel can be modified by alteration of the aerogel composition and/orby annealing.

Use of Aerogels for Anti-Fouling:

In one embodiment the fouling organisms comprises aquatic organismsselected from the group consisting of bacteria, protozoa, fungus, algaeand invertebrates. In one preferred embodiment the aquatic organism isselected from barnacles and mussels. In another embodiment the aquaticorganism are of the Cirripedia subclass including Balanus galeatus,Balanus amphitrite, Elminius modestus, Balanus improvisus and Balanusbalanoides.

In one preferred embodiment the aerogel which comprises one or moreencapsulated bioactive agents has an anti-fouling effect and oranti-epibiosis effect. Anti-fouling is the process of removing orinhibiting the accumulation of biofouling.

Biofouling or biological fouling is the undesirable accumulation ofmicroorganisms, plants, algae, and animals on surfaces such as submergedstructures like ships' hulls. Biofouling also occurs on the surfaces ofliving marine organisms, when it is known as epibiosis. Biofouling isalso found in membrane systems, such as membrane bioreactors and reverseosmosis spiral wound membranes. In the same manner it is found asfouling in cooling water cycles of large industrial equipments and powerstations.

Biofouling is divided into microfouling—biofilm formation and bacterialadhesion—and macrofouling—attachment of larger organisms, of which themain culprits are barnacles, mussels, polychaete worms, bryozoans, andseaweed. Together, these organisms form a fouling community.

Individually small, accumulated biofoulers can form enormous masses thatseverely diminish ships' maneuverability and carrying capacity. Foulingcauses huge material and economic costs in maintenance of marineculture,shipping industries, naval vessels, and seawater pipelines.

Biofouling can occur on any surface submerged in water such as forexample on ships. Other examples of surfaces that can be exposed tobiofouling are any installations, membranes, nets, measuring equipmentor other equipment in aquaculture.

Biofouling can also occur in groundwater wells where buildup can limitrecovery flow rates, and in the exterior and interior of ocean-layingpipes. In the latter case it has been shown to retard the seawater flowthrough the pipe and has to be removed with the tube cleaning process.

In one preferred embodiment the surface for application of theanti-fouling composition is a surface that is at least occasionallyimmersed in water, wherein said water includes fresh, salt or brackishwater. The surface can be selected from the group consisting of thesurfaces of vessels including boats and ships, ship hulls, off-shoreequipment, pipes, substructures of bridges, piers and aquaculturalapparatuses including fish farming nets.

In another preferred embodiment the aerogel which comprises one or moreencapsulated bioactive agents has an anti-bacterial effect. The aerogelwith the anti-bacterial effect can in one preferred embodiment beemployed in food production such as in the dairy industry. In anotherembodiment the aerogel with the anti-bacterial effect can be used inhospitals such as in an operating room.

Antimicrobial Effects of the Coating Composition

The coating compositions of the invention are capable of reducing and/oreliminating fouling in the form of microbial growth and/or the formationof bio-film on objects coated with the composition. The microbialorganisms can be e.g. bacteria, vira, fungal cells and slime molds. Foraquatic environments, the microbial organisms are marine organisms.

In selecting the at least one enzyme of the coating composition one musttake into consideration—among other things—the type of surface beingprotected, the environment in which the surface is found, and theorganism against which protection is being sought.

The general principle underlying the choice of enzyme to be immobilizedis that the abundance of a particular type of enzyme should beproportional to the probable frequency of surface contact with thetarget organism against which the antifouling species, including anantimicrobial species generated by the enzyme has anti-fouling efficacy.

Marine Antifouling Effects

As an example, a short-term protection against settling organisms in amarine environment can focus on deterring the formation of films thatare deposited by the settlement and growth of marine algae and bacteria.In this case, the bioactive materials to be incorporated on the surfacecan be distributed equally between a bactericide and an algaecide.

Accordingly, the antimicrobial effects of the compositions according tothe invention are directed to—among others—the following groups ofmicrobial organisms: Bacteria, fungi, algae, protozoa, porifera,coelenterata, platyhelminthes, nemertea, rotifera, bryozoa, brachiopoda,annelida, arthropoda, mollusca, echinodermata and chordata.

One interesting case is that of preventing growth and/or attachment to asurface of Vibrio species in an aquatic environment. Vibrio speciesoften cluster together due to the presence of an extracellularpolysaccharide (slime) that they synthesize. The best-known species ofVibrio is V. cholerae which causes cholera, a severe diarrhoeal diseaseresulting from a toxin produced by bacterial growth in the gut.Accordingly, the present invention in one preferred embodiment alsorelates to preventing and/or reducing the risk of cholera outbreaks inenvironments wherein V. cholerae is present. The method includes thestep of coating pipes, filters, tanks and the like with a compositionaccording to the invention comprising at least one oxidase and apolysaccharide degrading enzyme capable of degrading polysaccharidessecreted by Vibrio species including V. cholerae.

The development of an antifouling species, including an antimicrobialspecies which could eliminate only, for example, barnacles in an aqueousenvironment would be solving only part of the fouling problem. Studieson the temporal development of a fouling community have revealed thatbacteria are usually the first organisms to colonize a submergedsurface. Attached bacteria produce a secondary extracellular polymericadhesive, and eventually the surface of the substratum becomes coatedwith bacteria embedded within this extracellular matrix (collectivelyreferred to as a bacterial film).

The rate of subsequent colonization by other microorganisms, and bymarine invertebrate larvae, is often dependent upon the initialformation of a bacterial film. Consequently, the development of acoating composition capable of reducing and/or eliminating the processof bacterial film formation can be expected also to have a significantanti-fouling effect.

A small number of proteins and carbohydrates constitute the importantstructural elements of the cell wall of a wide range of microbialorganisms. Collagen, cellulose, and chitin are three abundant structuralpolymers. Chitin, for example, is an important constituent of the shellmatrix of the inarticulate Brachipoda, the exoskeleton of the Ectoprocta(e.g. Bryozoa), the walls of sponge gemmules (the dispersal stage of thesponge life cycle), the perisarc (the outer layer of the integument) ofhydrozoan coelenterates, the cell wall of fungi, and the cuticle of allarthropods. Additional relevant polysaccharides are mannans,galactomannans, alginates, laminarins, carregeenans (iota and kappa),and agars.

Any enzyme capable of degrading any one or more of the above polymers,including collagen and/or cellulose and/or chitin can therefore beincluded into the coating composition of the invention, optionally inthe absence of a substrate for such an enzyme, and preferably incombination with an oxidase, in the absence of a substrate for saidoxidase.

The integument of most fouling organisms is the principal organ ofpermanent post-metamorphic attachment and adhesion. Interference withthe synthesis of an important biochemical constituent of the cell wallor integument, or any degradation of such structural elements orinterference with the enzymatic processes involved in adhesion wouldtherefore exert a strong anti-fouling action.

As the bacterial and algae film production can well be a prerequisitefor most macrofouling, this term refers to the attachment of organismslarger than unicellular organisms to an aquatic surface. Should this bethe case, little or no enzyme or other chemical antifoulant capable ofdisrupting the attachment process of macrofouling organisms may need tobe included as microfouling does not take place.

However, in a region that is heavily populated with barnacle larvae,enzymes which specifically retard the settlement of the barnacle larvawould be more important and should be incorporated on a surface,preferably in larger proportion.

The coating compositions according to the invention in one embodimentresult in the formation of essentially one or more monolayers of enzymeslocated on the surface of an object. For example, an enzyme having amolecular weight of approximately 50,000 daltons would give a monolayerwhen spaced on a surface with a distance of approximately 40 angstromsbetween the centers of adjacent molecules. This spacing assumes a Stokesradius of approximately 20 angstroms. However, it is not essential thata complete monolayer is present. A desirable activity can be maintainedwith the spacing of bioactive compounds over greater distances. Aspacing of no more than 1,000 angstroms and more preferably no more than100 angstroms is preferred in order to insure that a biologically activechemical is available for reaction with a fouling organism at each pointof initial contact.

The coating compositions of the invention can be used in all types ofenvironments, including non-aquatic as well as aquatic environments,including sea-water, estuary, and fresh water environments. In additionto natural environments (i.e., those which are in free contact with andfreely exchange material with other parts of the biosphere without humanintervention), the term “aquatic environments” as used herein alsoincludes cooling towers, fresh and salt water piping systems,desalination and other filtration systems containing membrane “surfaces”subject to protection, and other aquatic environments which rely uponthe intervention of human beings for their creation and maintenance.

As used herein, the term “natural environment” includes ponds, lakes,dredged channels and harbors, and other bodies of water which wereinitially produced by the action of human beings but which do not relyupon human intervention for the supply of water into and out of suchenvironments.

While many fouling organisms, such as barnacles and algae, are wellknown to the general public, those skilled in the art will recognizethat the term fouling organism as used herein refers to any livingorganism which is capable of attaching to a surface in an aquaticenvironment.

The group of algae are very diverse and probably not related to oneanother. There are 6 divisions of algae, some unicellular and somemulticellular. In some taxonomic schemes, the last three divisions areincluded in the Kingdom Protista which includes all eukaryotic,unicellular organisms, regardless of their mode of nutrition.

Algae can be characterised with respect to e.g.:

-   -   1. Photosynthetic pigments. Some pigments mask the chlorophylls        and give their name to the common name of the division—Brown        algae. The accessory pigments participate with the PS II        reaction center.    -   2. Food storage chemistry is an important distinguishing        feature. Not all organisms store energy in the form of starch as        do most plants. There are unique storage chemicals for the        various division.    -   3. Flagella structure is a good distinguishing feature for those        division that have flagellated cell. The number of flagella,        morphology of the flagellum and its orientation characterize        divisions.    -   4. Cell wall chemistry is another distinguishing feature.    -   5. Sometimes the habitat for members of the division can be        important.

Rhodophyta are the red algae:

-   -   1. Pigments—the phycobolins, phycoerythrin and        phycocyaninare_the pigments that usually mask the chlorophyll a        that is common to all algae and the green plants.    -   2. Food storage materials—Floridean starch is a polysaccharide        material.    -   3. Cell wall materials—The red algae possess a microfibrillar        network of polysaccharide material (cellulose or some other)        embedded within a mucilaginous matrix such as agar. Some marine        forms may produce CaCO₃ in their walls to give them a rigid        structure.    -   4. Types and number of flagella—The red algae never produce        motile cells. Not only do they not produce motile cells, it        appears that they may never have had motile cells.    -   5. Habitat—The red algae are mostly marine organisms but a few        freshwater types do exist.    -   6. The life cycles of red algae are complicated by the presence        of a third generation type in addition the sporophyte and        gametophyte.

Phaeophyta are the brown algae. This group includes the kelps androckweeds:

-   -   1. Pigments—The Brown algae have fucoxanthin as an accessory        pigment to mask the chlorophyll a and c, giving them the        brownish color.    -   2. Food storage materials—Lamanarin is a polysaccharide food        storage material unique to the brown algae.    -   3. Cell wall materials include a mucilaginous material called        algin that is harvested from kelps.    -   4. Types and number of flagella—The brown algae have heterokont        flagellated cells. One is an anteriorly-oriented tinsel-type        flagellum and the other flagellum is a posteriorly-oriented        whiplash type.    -   5. Habitat—The brown algae are all marine organisms.    -   6. Several life cycle types are exemplified by the brown algae.        -   Ectocarpus is a filamentous alga that has an isomorphic            alternation of generations.        -   Laminaria is a kelp that has a heteromorphic alternation of            generations. The gametophyte is microscopic, whereas the            sporophyte is macroscopic.        -   Fucus is a rockweed that has gametic meiosis. There is no            alternation of generations for this organism. The            gametangia, antheridia and oogonia, are produced within a            conceptacle. Many conceptacles are located on a receptical            at the end of the dichotomously branched thallus. Meiosis            occurs in the production of the gametes.

Chlorophyta are the green algae. Because of the similarity inpigmentation, cell division, and food storage materials, the land plantsare thought to be derived from the Chlorophyta:

-   -   1. Pigments—Chlorophyll b is the accessory pigment.    -   2. Food storage materials are starch.    -   3. Cell wall materials—are primarily cellulose but some marine        forms may add CaCO₃.    -   4. Types and number of flagella of the chlorophyta are isokonts        with whiplash flagella.    -   5. Habitat of chlorophyta is freshwater and marine.    -   6. Taxonomy of the chlorophyta is divided into three classes        based on method of cell division, insertion of flagella and        internal cell structure.        -   Method of cell division refers to the production of a            phragmoplast. or a phy phycoplast.        -   Insertion of flagella are either apical or subapical.        -   Internal cell structure refers to the possession of a system            of microtubules found near the flagella apparatus. Also the            possession of peroxisomes involved in photoresiration.    -   7. Classes of Chlorophyta        -   Charophyceae are the group most like the land plants. They            undergo mitosis by formation of a phragmoplast, possess the            microtubular system characteristic of land plants, and have            subapically inserted flagella. Example organisms in this            group are Spyrogyra, the desmids and Coleochaeta.        -   The Ulvaphyceae are mostly marine organisms that have an            alternation of generation. The life cycle of Ulva has an            isomorphic alternation of generations with sporic meiosis.            These organisms produce a phycoplast when undergoing cell            division and the nuclear envelope persists during division.        -   Chlorophyceae produce a phycoplast when undergoing cell            division and the nuclear envelope persists during division.            There are many forms that have zygotic meiosis like            Chlamydamonas.

Chrysophyta are unicellular algae:

-   -   1. Characteristics of the Chrysophyta indicate a similarity with        the brown algae. There are three classes of chrysophyta.        -   Pigments include chlorophyll a and chlorophyll c. These are            usually masked by an abundance of a brownish pigment,            fucoxanthin.        -   Food reserve in the Chrysophyta is called chrysolaminarin—a            carbohydrate.        -   The cell of chrysophytes may be naked or they may have cell            walls of cellulose. Some members have silica scales or            shells.    -   2. Classes of Chrysophyta        -   Chrysophyceae are primarily freshwater planktonic organisms.            They lack a clearly defined cell wall but have silica            scales. Many of these organisms have flagella.        -   Bacillariophyceae are the diatoms. These are important            phytoplanktonic organisms in freshwater and marine            environments. They are characterized by the presence of            silica cell walls with intricate markings. They have            chlorophyll a and c and fucoxanthin which gives them a            brownish color. When they undergo sexual reproduction, the            only flagellated cell appears, a males sperm cell. It has            two flagella, one whiplash and one tinsel type.        -   Xanthophyceae are the yellow green algae because they lack            fucoxanthin and the greenish colors show. Vaucheria, which            you saw in lab belongs to this class.

Pyrrophyta are important phytoplanktonic organisms in freshwater andmarine habitats:

-   -   1. Characteristics of Pyrrophyta        -   The dinoflagellates contain chlorophyll a and c and a            brownish pigment called peridinin.        -   The food storage material of the pyrrophyta is starch.        -   The cell walls of those that possess them are in the form of            cellulosic plates and hence the name armored dinoflagellates            given to some members of the phylum.        -   The pyrrophyta have two flagella. One flagellum encircles            the cell like a belt. The other flagellum trails behind the            cell.    -   2. Features of the dinoflagellates        -   Some of these organisms are responsible for the poisonous            red tide.        -   Some of these organisms are capable of bioluminescence.

Euglenophyta are unicellular algae that lack a cell wall:

-   -   1. Characteristics of the Euglenophyta        -   The euglenoids posses chlorophyll a and b and carotenoids.            They have the same grass green color as the green algae.        -   The food storage material of the euglenoids is paramylon, a            polysaccharide material        -   The euglenophyta lack cell walls. Instead they have a            proteinaceous coating called the pellicle. They are capable            of changing shape because they lack the cell wall.        -   The euglenoids have two flagella but only one flagellum            emerges from a gullet at the tip of the cell. The other            short flagellum is basically nonfunctional as a swimming            aid.

Prevention and/or elimination or at least substantial reduction ofmicrofouling by all or some of the above algae is within the scope ofthe present invention.

The term microfouling is used to denote the attachment of unicellularorganisms, such as bacteria and algae, to the submerged surface. Thesemicrofouling organisms can, in some cases, secrete chemical signalswhich attract further organism to the surface, thereby increasing therate of fouling. Macrofoulers, such as barnacles, become attached to thesurface after the formation of the initial microfouling layer.

As microfouling may occur before the macrofouling, any process whichinterferes with the attachment of microbial organisms to aquaticsurfaces would decrease the total amount of fouling which takes place.Thus, an active ingredient capable of preventing the attachment ofbarnacles operates at the end of the fouling chain while an activespecies which operates to prevent the attachment of unicellularorganisms such as bacteria operates at the beginning of the foulingchain. Accordingly, species which prevent microfouling may have someinhibitory effect against settlement of all types of fouling. One suchparticularly preferred antifouling species, including an antimicrobialspecies is peroxides, such as hydrogen peroxide, produced by oxidases.

Additional antifouling organisms the growth of which is capable of beingcontrolled by the means of the present invention as described hereinincludes, but is not limited to crustaceans and other marine hardgrowth, such as:

Tube Worms: polychaetes; phylum Annelida; subclass Eunicea; familySerpulidaeMussels: bivalves; phylum Mollusca; subclass Pteriomorphia; familyMytilidaeClams: bivalves; phylum Mollusca; subclass Hterodonta; family VeneridaeBryozoans: bryozoans; phylum Bryozoa; suborder Anasca and Ascophora;genus SchizoporellaBarnacles: crustaceans; phylum Arthropoda; subphylum Crustacea

However, as is clear from the description herein above, the inventionalso has utility against soft growth, which can impede e.g. theefficiency of hull forms, damage substrates of marine structures,generally shorten the viable life span of equipment, and escalate thecost of operation. Examples of these soft growth forms include:

Algae (Botanus): Padina, and Codium Bryozoans (Animal): Bugula NeretinaHydroids (Animal): Obelia Sabellids (Animal): Delaya Marina (MarineBacteria): Zibria

The compositions, coatings and/or paints according to the presentinvention may also function by direct attack on the surface film,disrupting its polymeric structure through e.g. hydrolysis of theproteins and polysaccharides of the film. This would interrupt the chainof events that ultimately leads to the accumulation of large amounts ofmarine organisms (including bacteria, fungi, barnacles, etc.) on e.g.the hull of the ship.

Such attack may be accomplished by the use of extracellular enzymes thatdisrupt the polysaccharides and proteins that make up the surface film.Key hydrolytic enzymes in this respect are proteases, alpha-amylases,amyloglycosidases and xylanases. Alternatively, the coatings and/orpaints may function by modifying the surface tension of the marinesurface to which the coatings and/or paints have been applied. Such achange in the surface tension may disrupt the colonization of thesurface by undesirable marine organisms.

The methods and compositions disclosed herein may be used on a varietyof surfaces, including but not limited to boat hulls, marine markers,bulkheads, pilings, water inlets, floors, roofs, and shingles. Forexample, the methods and compositions may be used to minimize fouling ofmarine markers. Such markers constitute a large category of floatingobjects and are greatly impaired by the accumulation of marine growth.

Similarly, the methods and compositions may be used on marine bulkheads.The accumulation of marine growth on bulkhead structures is detrimentalto the bulkhead structure over the long term. Furthermore, the growthcauses significant short term effects that are aesthetically displeasingand dangerous. Moreover, the harsh abrasive characteristics of the hardgrowth can result in major damage to vessels.

Similarly, the present invention can be used to minimize blockages dueto fouling by marine growth of heat exchangers, evaporators, condensersand fire and flushing systems, thus resulting in significant decreasesin maintenance costs for all categories of marine structures.

Compositions and/or paints according to the invention may includevarious hydrolytic enzymes, although it is possible to practice theinvention without such hydrolytic enzymes. Examples of suitable enzymesinclude proteases, including subtilisins such as e.g. alcalase,amylases, amyloglycosidases, xylanases and other hydrolytic enzymesknown in the art. The hydrolytic enzymes selected should act to preventor reduce attachment by unwanted or undesirable marine organisms. Thehydrolytic enzymes chosen should be able to survive and flourish in themarine environment to which they will be exposed.

Compositions and/or paints according to the invention include theabove-mentioned enzymes in an amount effective to reduce the growth ofunwanted or undesirable microorganisms. Such compositions and/or paintsmay be in a variety of forms, including paints, lacquers, pastes,laminates, epoxies, resins, waxes, gels, and glues in addition to otherforms known to one of skill in the art.

The compositions and/or paints may be polymeric, oligomeric, monomeric,and may contain cross-linkers or cure promoters as needed. Suchcompositions and/or paints may contain other additives, in addition tothose mentioned above, to accomplish purposes known to one of skill inthe art. Such other additives include preservatives, pigments, dyes,fillers, surfactants, and other additives known to one of skill in theart.

Selected Antifouling Species

Peroxides in general constitute one much preferred group of antifoulingspecies, including an antimicrobial species according to the invention.Hydrogen peroxide is an example of a presently most preferredantifouling species, including an antimicrobial species.

Any enzyme-compound combination capable of producing hydrogen peroxidecan be used, including a combination wherein the enzyme is an oxidaseand the compound can be oxidized by said oxidase.

A combination of said oxidase with said compounds to be oxidized therebyincludes such combinations as (enzyme-substrate) malate oxidase-malicacid; glucose oxidase-glucose; hexose oxidase-glucose; cholesteroloxidase-cholesterol; arylalcohol oxidase-arylalcohol: galactoseoxidase-galactose; alcohol oxidase-alcohol; lathosteroloxidase-lathosterol; aspartate oxidase-aspartic acid; L-amino-acidoxidase-L-amino acid; D-amino-acid oxidase-D-amino acid; amineoxidase-amine; D-glutamate oxidase-glutamine; ethanolamineoxidase-ethanolamine; NADH oxidase-NADH; urate oxidase (uricase)-uricacid; superoxide dismutase-superoxide radical; and so forth.

The enzymatic reaction between said oxidase and the compound yieldshydrogen peroxide. The enzymatic reaction can proceed when either oxygenor oxygen and water are present in an external environment contactingthe coating composition according to the invention.

The above-mentioned oxygen is supplied not only from atmospheric air butalso from e.g. seawater containing dissolved oxygen. The enzymaticreaction of the invention occurs in an external environment includingseawater with the result that hydrogen peroxide is produced in saidenvironment.

Additional preferred species having antimicrobial activity includes, butis not limited to, carboxyl group-containing species, hydroxylgroup-containing species, amino group-containing species, aldehydegroup-containing species, and decomposition products of chitosan.

The carboxyl group-containing species includes a variety of organic acidspecies, e.g. aliphatic acids such as formic acid, acetic acid,propionic acid, butyric acid, caproic acid, caprylic acid, capric acid,lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid,linolenic acid, monochloroacetic acid, monofluoroacetic acid, sorbicacid, undecylenic acid, etc.; dibasic acids such as oxalic acid etc.;aromatic carboxylic acids such as benzoic acid, p-chlorobenzoic acid,p-hydroxybenzoic acid, salicylic acid, cinnamic acid, etc.; and theirderivatives and halides. Any enzyme-compound combination capable ofproducing a carboxyl group-containing species can be applied.

The ester bond-containing species mentioned above is not particularlyrestricted in kind but includes, among others, esters of any of saidcarboxyl group-containing species with aliphatic alcohols such as methylalcohol, ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol,caproyl alcohol, caprylyl alcohol, capryl alcohol, lauryl alcohol,myristyl alcohol, palmityl alcohol, oleyl alcohol, etc.; esters of anyof said carboxyl group-containing species with aromatic alcohols such asphenol, benzyl alcohol, etc.; esters of any of said carboxylgroup-containing species with polyhydric alcohols such as ethyleneglycol, glycerol, etc.; and esters of any of said carboxylgroup-containing species with derivatives or halides of said aliphaticalcohols, aromatic alcohols, or polyhydric alcohols.

The ester bond-containing species mentioned above is hydrolyzed by saidesterase in the above-mentioned coating composition to produce saidcarboxylic group-containing species. This enzymatic reaction can proceedwhen water is present in the reaction system, as follows.

R₁COOR₂+H₂O=>R₁COOH+R₂OH

In the above reaction scheme, R₁ represents carboxylic residue and R₂represents an alcohol residue.

When the above coating composition is applied to an object, theantimicrobial effect is achieved when e.g. moisture from the atmosphereis provided to the reaction resulting in the production of anantifouling species, including an antimicrobial species. When thecoating composition is applied to an object to be placed in an aqueousenvironment e.g. in water such as seawater, the reaction resulting inthe production of antifouling species, including an antimicrobialspecies takes place in said water.

The amide bond-containing species mentioned above includes, but is notlimited to, amides of any of said carboxyl group-containing species withaliphatic amines such as butylamine, hexylamine, octylamine, decylamine,laurylamine, stearylamine, oleylamine, etc.; and amides of any saidcarboxyl group-containing species with aromatic amines such as aniline,toluidine, xylidine, and alkylanilines such as hexylaniline,octylaniline, nonylaniline, dodecylaniline, and so forth.

The hydroxyl group-containing species mentioned above includes, but isnot limited to, aliphatic alcohols such as methyl alcohol, ethylalcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutylalcohol, pentyl alcohol, isopentyl alcohol, hexyl alcohol, etc.;aromatic alcohols such as phenol, chlorophenol, and alkylphenols such ascresol, xylenol, etc., resorcinol, benzyl alcohol, etc.; and thederivatives and halides of said aliphatic or aromatic alcohols.

Any enzyme-compound combination capable of producing the hydroxylgroup-containing species can be applied. In one embodiment, the enzymeis an esterase and the compound is an ester bond-containing species. Theesterase and the ester bond-containing species includes the speciesmentioned hereinbefore, but is not limited to these species.

The amino group-containing species mentioned above includes, but is notlimited to aliphatic amines such as butylamine, hexylamine, octylamine,decylamine, laurylamine, stearylamine, oleylamine, cyclohexylamine,etc.; and aromatic amines such as aniline, toluidine, xylidine,p-n-hexylaniline, p-n-octylaniline, p-nonylaniline, p-dodecylaniline,and so forth.

Any enzyme-compound combination capable of producing said aminogroup-containing species can be used. Preferred is the case in which theenzyme is an amidase including a protease, and the compound is an amidebond-containing species including apolypeptide. The amidase and theamide bond-containing species includes the species mentionedhereinbefore, but is not limited to these species.

The aldehyde group-containing species includes, but is not limited toaliphatic aldehydes such as formaldehyde, glyoxal, succinaldehyde,glutaraldehyde, capronaldehyde, caprylaldehyde, caprinaldehyde,laurinaldehyde, stearinaldehyde, oleinaldehyde, etc.; benzaldehyde andits derivatives such as p-n-hexylbenzaldehyde, p-octylbenzaldehyde,p-oleylbenzaldehyde, vaniline, piperonal, etc.; salicylaldehyde,cinnamaldehyde, and so forth.

Any enzyme-compound combination capable of producing said aldehydegroup-containing species can be used, including the case in which theenzyme is alcohol dehydrogenase and the compound is an aliphaticalcohol, e.g. methanol, ethanol, etc.; the case in which the enzyme isalcohol oxidase and the compound is an aliphatic alcohol such asmethanol, ethanol, etc.; the case in which the enzyme is arylalcoholdehydrogenase and the compound is an aromatic alcohol such as phenol,cresol, etc.; and the case in which the enzyme is amine oxidase and thecompound is an aliphatic amine such as butylamine, hexylamine, and soforth.

Any enzyme-compound combination capable of producing a decompositionproduct of chitosan can be applied. Preferred is the case in which theenzyme is a chitosan-decomposing enzyme and the compound is chitosan.

Enzyme Concentrations

In one preferred embodiment the aerogel comprises from 1 to 90 weight %enzyme, such as from 1 to 85 weight %, for example from 1 to 80 weight%, such as from 1 to 75 weight %, for example from 1 to 70 weight %,such as from 1 to 65 weight %, for example from 1 to 60 weight %, suchas from 1 to 55 weight %, for example from 1 to 50 weight %, such asfrom 1 to 45 weight %, for example from 1 to 40 weight %, such as from 1to 35 weight %, for example from 1 to 30 weight %, such as from 1 to 25weight %, for example from 1 to 20 weight %, such as from 1 to 25 weight%, for example from 1 to 20 weight %, such as from 1 to 15 weight %, forexample from 1 to 10 weight %, such as from 1 to 5 weight %, for examplefrom 1 to 4 weight %, such as from 1 to 4 weight %, for example from 1to 3 weight %, such as from 1 to 2 weight %, for example from 5 to 90weight %, such as from 10 to 90 weight %, for example from 15 to 90weight %, such as from 20 to 90 weight %, for example from 25 to 90weight %, such as from 30 to 90 weight %, for example from 35 to 90weight %, such as from 40 to 90 weight %, for example from 45 to 90weight %, such as from 50 to 90 weight %, for example from 55 to 90weight %, such as from 60 to 90 weight %, for example from 65 to 90weight %, such as from 70 to 90 weight %, for example from 75 to 90weight %, such as from 80 to 90 weight %, for example from 85 to 90weight %, such as from 1 to 5 weight %, for example from 5 to 10 weight%, such as from 10 to 15 weight %, for example from 15 to 20 weight %,such as from 20 to 25 weight %, for example from 25 to 30 weight %, suchas from 30 to 35 weight %, for example from 35 to 40 weight %, such asfrom 40 to 45 weight %, for example from 45 to 50 weight %, such as from50 to 55 weight %, for example from 55 to 60 weight %, such as from 60to 65 weight %, for example from 65 to 70 weight %, such as from 70 to75 weight %, for example from 75 to 80 weight %, such as from 80 to 85weight %, for example from 85 to 90 weight %.

The present invention relates in one preferred embodiment to a methodfor increasing the amount of a bioactive agent in a coating compositioncomprising an organic solvent, said method comprising the steps of:

-   -   a) providing a coating composition comprising an organic        solvent,    -   b) providing an aerogel comprising one or more biologically        active enzymes entrapped therein,    -   c) mixing the coating composition provided in step a) with the        aerogel comprising one or more biologicaly enzymes entrapped        therein as provided in step b), thereby    -   d) obtaining a coating composition comprising an organic solvent        and an aerogel comprising one or more biologically active        enzymes entrapped therein,        wherein said one or more biologically active enzymes are present        in a higher concentration and/or possesses a higher biological        activity than would have been the case had said one or more        enzymes not been entrapped in said aerogel structure

Additional Components of Coating Compositions of the Invention

In one preferred embodiment the anti-fouling composition comprising anaerogel further comprises at least one algicide, herbicide, fungicide,molluscicide or other compound exhibiting anti-fouling activity.

In one preferred embodiment the anti-fouling composition comprising anaerogel further comprises a binder component, suitable for marineapplications and a pigment.

The coating compositions of the invention described herein above canfurther comprise a binder to immobilise at least one of theconstituents, optionally to immobilise the enzymes.

The coating compositions of the present invention can be formulated ascoatings, lacquers, stains, enamels and the like, hereinafter referredto generically as “coating(s)”.

Preferably, the coating composition is formulated for treatment of asurface selected from outdoor wood work, external surface of a centralheating system, and a hull vehicle should not interfere with theactivity of the at least one enzyme(s) and/or any additional antifoulantcompound.

Suitable solvents for coating compositions are disclosed e.g. in U.S.Pat. No. 5,071,479 and include water and organic solvents includingaliphatic hydrocarbons, aromatic hydrocarbons, such as xylene, toluene,mixtures of aliphatic and aromatic hydrocarbons having boiling pointsbetween 100° C. and 320° C., preferably between 150° C. and 230° C.;high aromatic petroleum distillates, e.g., solvent naptha, distilled taroil and mixtures thereof; alcohols such as butanol, octanol and glycols;vegetable and mineral oils; ketones such as acetone; petroleum fractionssuch as mineral spirits and kerosene, chlorinated hydrocarbons, glycolesters, glycol ester ethers, derivatives and mixtures thereof.

The solvent may be apolar or polar, such as water, optionally inadmixture with an oily or oil-like low-volatility organic solvent, suchas the mixture of aromatic and aliphatic solvents found in whitespirits, also commonly called mineral spirits.

The solvent may typically contain at least one of a diluent, anemulsifier, a wetting agent, a dispersing agent or other surfacebioactive agent. Examples of suitable emulsifiers are disclosed in U.S.Pat. No. 5,071,479 and include nonylphenol-ethylene oxide ethers,polyoxyethylene sorbitol esters or polyoxyethylene sorbitan esters offatty acids, derivatives and mixtures thereof.

Any suitable surface coating material may be incorporated in thecomposition and/or coating of the present invention. Examples oftrade-recognized coating materials are polyvinyl chloride resins in asolvent based system, chlorinated rubbers in a solvent based system,acrylic resins and methacrylate resins in solvent based or aqueoussystems, vinyl chloride-vinyl acetate copolymer systems as aqueousdispersions or solvent based systems, butadiene copolymers such asbutadiene-styrene rubbers, butadiene-acrylonitrile rubbers, andbutadiene-styrene-acrylonitrile rubbers, drying oils such as linseedoil, alkyd resins, asphalt, epoxy resins, urethane resins, polyesterresins, phenolic resins, derivatives and mixtures thereof.

The composition and/or coating of the present invention may containpigments selected from inorganic pigments, such as titanium dioxide,ferric oxide, silica, talc, or china clay, organic pigments such ascarbon black or dyes insoluble in sea water, derivatives and mixturesthereof.

The coating composition of the present invention can also containplasticisers, rheology characteristic modifiers, other conventionalingredients and mixtures thereof.

The coating composition of the present invention optionally furthercomprise an adjuvant conventionally employed in compositions used forprotecting materials exposed to an aquatic environment. These adjuvantsmay be selected from additional fungicides, auxiliary solvents,processing additives such as defoamers, fixatives, plasticisers,UV-stabilizers or stability enhancers, water soluble or water insolubledyes, color pigments, siccatives, corrosion inhibitors, thickeners orantisettlement agents such as carboxymethyl cellulose, polyacrylic acidor polymethacrylic acid, anti-skinning agents, derivatives and mixturesthereof.

In one embodiment the present invention provides a marine anti-foulantcomprising the coating composition as described above. Preferably, theanti-foulant is self-polishable.

In one embodiment of the present invention, the enzyme is preferablyencapsulated, such as encapsulated by a semi-permeable membrane. Onetype of enzymes may be encapsulated individually independently of othertypes of enzymes, or the enzymes may be encapsulated together. Theencapsulating material may be selected such that on contact with afoulant, the enzyme may be released. In this way, a composition may beprovided which only provides an anti-foulant species or increasesprovision of an anti-foulant compound when contacted with a foulant.Alternating layers of anti-foulant species and encapsulation materialensures a sequential release of enzymes.

The composition of the present invention can be provided as aready-for-use product or as a concentrate. The ready-for-use product maybe in the form of an aqueous solution, aqueous dispersion, oil solution,oil dispersion, emulsion, or an aerosol preparation. The concentrate canbe used, for example, as an additive for coating, or can be dilutedprior to use with additional solvents or suspending agents.

An aerosol preparation according to the invention may be obtained in theusual manner by incorporating the composition of the present inventioncomprising or dissolved or suspended in, a suitable solvent, in avolatile liquid suitable for use as a propellant.

As discussed in U.S. Pat. No. 5,071,479, the coating composition of thepresent invention can also include additional ingredients known to beuseful in preservatives and/or coatings. Such ingredients includefixatives such as carboxymethylcellulose, polyvinyl alcohol, paraffin,co-solvents, such as ethylglycol acetate and methoxypropyl acetate,plasticisers such as benzoic acid esters and phthlates, e.g., dibutylphthalate, dioctyl phthalate and didodecyl phthalate, derivatives andmixtures thereof. Optionally dyes, color pigments, corrosion inhibitors,chemical stabilizers or siccatives (dryers) such as cobalt octate andcobalt naphthenate, may also be included depending on specificapplications.

The composition and/or coating of the present invention can be appliedby any of the techniques known in the art including brushing, spraying,roll coating, dipping and combinations thereof.

Compositions of the present invention can be prepared simply by mixingthe various ingredients at a temperature at which they are not adverselyaffected. Preparation conditions are not critical. Equipment and methodsconventionally employed in the manufacture of coating and similarcompositions can be advantageously employed.

Paint

In another embodiment the aerogel comprising one or more bioactiveagents is used as an agent in a paint or any other preservation forprotection of any type of surface such as wood, metal, stone, bricks,concrete and plastic. The present invention e.g. relates to housepainting and wood or metal protection.

In one preferred embodiment the paint or other type of coatingcomposition comprises aerogel particles.

In one preferred embodiment the paint or other type of coatingcomposition comprises one or more premade aerogel(s). After mixing ofthe one or more aerogels with the paint or other type of coatingcomposition the physical and chemical properties of the one or moreaerogels may be affected.

In one preferred embodiment an antifouling paint composition comprisesat least one subtilisin (EC 3.4.21.62), said subtilisin having thefollowing characteristics: (i) optimum activity at a pH in the range ofabout 7-10, and (ii) optimum activity at a temperature in the range ofabout 55-65° C. In another embodiment the antifouling paint compositioncomprises the subtilisin Alcalase®. In one preferred embodiment theantifouling paint composition comprises the Alcalase® Alcalase 2.5 L,Type DX®.

Paint is any liquid, liquifiable, or mastic composition which afterapplication to a surface in a thin layer is converted to an opaque solidfilm.

The paint or preservative is used to protect, decorate (such as addingcolor), or add functionality to an object or surface by covering it witha pigmented coating. An example of protection is to retard corrosion ofmetal. An example of decoration is to add festive trim to a roominterior. An example of added functionality is to modify lightreflection or heat radiation of a surface. Another example offunctionality would be the use of color to identify hazards or functionof equipment and pipelines.

Paint can be applied to almost any kind of object. It is used, amongmany other uses, in the production of art, in industrial coating, as adriving aid (road surface marking), or as a barrier to prevent corrosionor water damage. Paint is a semifinished product, or intermediate goodas the final product is the painted article itself.

Paint can also be mixed with glaze to create various textures andpatterns. This process is referred to as faux finish.

The present invention also relates to in-can preservation of paint.

Components of Paint

There are three primary components to a paint:

1) Pigments;

2) Binder, also known as non-volatile vehicle or resin and3) Vehicle, also known as volatile vehicle, also called solvent.

Pigment

Pigments impart such qualities as color and opacity, and influenceproperties such as gloss, film flow, and protective abilities. Pigmentcan generally be categorized into two main types: Prime or hidingpigments and Inert or extender pigments.

The main modern white hiding pigment is Titanium dioxide. Zinc oxide isa weaker white pigment with some important usages. Color hiding pigmentsfall also into two main categories, those being Inorganic, mostly dullerearth tone colors, and Organic, generally brighter but more expensivecolors.

Inert pigments break down into natural or synthetic types. Naturalpigments include various clays, calcium carbonate, mica, silicas, andtalcs. Synthetics would include calcined clays, blanc fix, precipitatedcalcium carbonate, and synthetic silicas.

Hiding pigments, in making paint opaque, also protect the substrate fromthe harmful effects of ultraviolet light.

Some pigments are toxic, such as the lead pigments that are used in leadpaint. Paint manufacturers began replacing white lead pigments with theless toxic substitute, which can even be used to color food, titaniumwhite (titanium dioxide), even before lead was functionally banned inpaint for residential use in 1978 by the U.S. Consumer Product SafetyCommission.

Titanium dioxide was first used in paints in the 19th century. Thetitanium dioxide used in most paints today is often coated with siliconor aluminum oxides for various reasons such as better exteriordurability, or better hiding performance (opacity) via better efficiencypromoted by more optimal spacing within the paint film. Opacity is alsoimproved by optimal sizing of the titanium dioxide particles.

The present invention relates to an antifouling coating compositioncomprising one or more aerogels, and one or more bioactive agents andfurther comprising any pigment described in the prior art or anycombination thereof.

Binder

The binder, or resin, is the actual film forming component of paint. Itimparts adhesion, binds the pigments together, and strongly influencessuch properties as gloss potential, exterior durability, flexibility,and toughness.

Binders include synthetic or natural resins such as acrylics,polyurethanes, polyesters, melamine resins, epoxy, or oils.

Binders can be categorized according to drying, or curing, mechanism.The four most common are simple solvent evaporation, oxidativecrosslinking, catalyzed polymerization, and coalescence.

Note that drying and curing are two different processes. Dryinggenerally refers to evaporation of vehicle, whereas curing refers topolymerization of the binder. Depending on chemistry and composition,any particular paint may undergo either, or both processes. Thus, thereare paints that dry only, those that dry then cure, and those that donot depend on drying for curing.

Paints that dry by simple solvent evaporation contain a solid binderdissolved in a solvent; this forms a solid film when the solventevaporates, and the film can re-dissolve in the solvent again. Classicnitrocellulose lacquers fall into this category, as do non-grain raisingstains composed of dyes dissolved in solvent.

Paints that cure by oxidative crosslinking are generally single packagecoatings that when applied, the exposure to oxygen in the air starts aprocess that crosslinks and polymerizes the binder component. Classicalkyd enamels would fall into this category.

Paints that cure by catalyzed polymerization are generally two packagecoatings that polymerize by way of a chemical reaction initiated bymixing resin and hardener, and which cure by forming a hard plasticstructure. Depending on composition they may need to dry first, byevaporation of solvent. Classic two package epoxies or polyurethaneswould fall into this category.

Latex paints cure by a process called coalescence where first the water,and then the trace, or coalescing, solvent, evaporate and draw togetherand soften the latex binder particles together and fuse them togetherinto irreversibly bound networked structures, so that the paint will notredissolve in the solvent/water that originally carried it.

Recent environmental requirements restrict the use of Volatile OrganicCompounds (VOCs), and alternative means of curing have been developed,particularly for industrial purposes. In UV curing paints, the solventis evaporated first, and hardening is then initiated by ultravioletlight. In powder coatings there is little or no solvent, and flow andcure are produced by heating of the substrate after application of thedry powder.

The present invention relates to an antifouling coating compositioncomprising one or more aerogels, and one or more bioactive agents andfurther comprising any binder described in the prior art or anycombination thereof.

Vehicle, or Solvent

The main purpose of the vehicle is to adjust the viscosity of the paint.It is volatile and does not become part of the paint film. It can alsocontrol flow and application properties. Its main function is as thecarrier for the non volatile components.

Water is the main vehicle for water based paints.

Solvent based, sometimes called oil based, paints can have variouscombinations of solvents as the vehicle, including aliphatics,aromatics, alcohols, and ketones. These include organic solvents such aspetroleum distillate, alcohols, ketones, esters, glycol ethers, and thelike. Sometimes volatile low-molecular weight synthetic resins alsoserve as diluents.

The present invention relates to an antifouling coating compositioncomprising one or more aerogels, and one or more bioactive agents andfurther comprising any vehicle or solvent described in the prior art orany combination thereof.

Additives

Besides the three main categories of ingredients, paint can have a widevariety of miscellaneous additives, usually added in very small amounts.Some examples include additives to improve wet edge, improve pigmentstability, impart antifreeze properties, control foaming, controlskinning, etc. Other additives might be thickeners, coalescent solvents,or biocides to fight bacterial growth.

The present invention relates to an antifouling coating compositioncomprising one or more aerogels, and one or more bioactive agents andfurther comprising any coating composition additives described in theprior art or any combination thereof.

Fillers serve to thicken the film, support its structure and simplyincrease the volume of the paint. Not all paints include fillers.Pigments that also function as fillers are called simply “pigments”;“fillers” are generally color-neutral and opaque. It is necessary toadjust the resulting off-white color with pigments to give the desiredcolor. Common fillers are cheap and inert, such as talc, lime, baryte,clay, etc. Depending on the paint, most of the paint film may consist ofpigment/filler and binder, the rest being other additives.

Besides pigments and dyes, other types of additives include catalysts,thickeners, stabilizers, emulsifiers, texturizers, adhesion promoters,flatteners (de-glossing agents), and the like.

After application, the paint solidifies and becomes tack-free. Dependingon the type of binder, this hardening may be a result of curing(polymerization), evaporation, or even phase change brought about bycooling. In oil-based paint, curing takes the form of oxidation, forexample oxidation of linseed oil to form linoxin to create a varnish.Other common cured films are prepared from crosslinkers, such aspolyurethane or melamine resins, reacted with acrylic polyester orpolyurethane resins, often in the presence of a catalyst which serves tomake the curing reaction proceed more quickly or under milderconditions. These cured-film paints can be either solvent-borne orwaterborne.

Latex paint is a water-based dispersion of sub-micron polymer particles.The term “latex” in the context of paint simply means an aqueousdispersion; latex rubber (the sap of the rubber tree that hashistorically been called latex) is not an ingredient. These dispersionsare prepared by emulsion polymerization. When the water evaporates, thepolymer particles coalesce to form a solid film. The polymer itselfresists water (and typically some other solvents). Residual surfactantsin the paint as well as hydrolytic effects with some polymers cause thepaint to remain susceptible to softening and, over time, degradation bywater.

Still other films are formed by cooling of the binder. For example,encaustic or wax paints are liquid when warm, and harden upon cooling.

The present invention relates to an antifouling coating compositioncomprising one or more aerogels, and one or more bioactive agents andfurther comprising any miscellaneous coating composition agent describedin the prior art or any combination thereof.

Product Variants

-   -   Primer is a preparatory coating put on materials before        painting. Priming ensures better adhesion of paint to the        surface, increases paint durability, and provides additional        protection for the material being painted.    -   Varnish and shellac provide a protective coating without        changing the color. They are paints without pigment.    -   Wood stain is a type of paint that is very “thin,” that is, low        in viscosity, and formulated so that the pigment penetrates the        surface rather than remaining in a film on top of the surface.        Stain is predominantly pigment or dye and solvent with little        binder, designed primarily to add color without providing a        surface coating.    -   Lacquer is usually a fast-drying solvent-based paint or varnish        that produces an especially hard, durable finish.    -   An enamel paint is a paint that dries to an especially hard,        usually glossy, finish. Enamel can be made by adding varnish to        oil-based paint.    -   A Glaze is an additive used with paint to slow drying time and        increase translucency, as in Faux Painting and Art Painting.    -   A Roof coating is a fluid applied membrane which has elastic        properties that allows it to stretch and return to their        original shape without damage. It provides UV protection to        polyurethane foam and is widely used as part of a roof        restoration system.    -   Fingerpaint    -   Inks are similar to paints, except they are typically made using        dyes exclusively (no pigments), and are designed so as not to        leave a thick film of binder.    -   Titanium dioxide is extensively used for both house paint and        artist's paint, because it is permanent and has good covering        power. Titanium oxide pigment accounts for the largest use of        the element. Titanium paint is an excellent reflector of        infrared, and is extensively used in solar observatories where        heat causes poor seeing conditions.    -   Anti-Graffiti paints are used to defeat the marking of surfaces        by graffiti artists. There are two categories, sacrificial and        non-bonding. Sacrificial coatings are clear coatings that allow        the removal of graffiti, usually by pressure washing the surface        with high-pressure water, removing the graffiti, and the coating        (hence, sacrificed.) They must be re-applied afterward for        continued protection. This is most commonly used on        natural-looking masonry surfaces, such as statuary and marble        walls, and on rougher surfaces that are difficult to clean.        Non-bonding coatings are clear, high-performance coatings,        usually catalyzed polyurethanes, that allow the graffiti very        little to bond to. After the graffiti is discovered, it can be        removed with the use of a solvent wash, without damaging the        underlying substrate or protective coating. These work best when        used on smoother surfaces, and especially over other painted        surfaces, including murals.    -   Anti-climb paint is a non-drying paint that appears normal while        still being extremely slippery. It is usually used on drainpipes        and ledges to deter burglars and vandals from climbing them, and        is found in many public places. When a person attempts to climb        objects coated with the paint, it rubs off onto the climber, as        well as making it hard for them to climb.    -   No-VOC paints, which are solvent-free paints that do not contain        volatile organic compounds, have been available since the late        1980s. Low VOC paints, which typically contain anywhere between        0.3%-5.0% VOCs as coalescent, or coalescing solvent have been        available since the 1960s.

Preferred Methods and Uses of the Invention

Preferred uses of the present invention include the following methods,but is not limited thereto:

Method for treating a surface contacted by fouling organisms, or asurface at risk of such contact, said method comprising the steps ofcontacting the surface with a composition according to the inventionwith an effective amount of said composition or coating composition,wherein said contacting results in eliminating said fouling or at leastreducing said fouling.

Method for preventing or reducing fouling of a surface, said methodcomprising the steps of contacting the surface with a compositionaccording to the invention with an effective amount of said compositionor coating composition or hygienic composition, wherein said contactingresults in preventing or reducing fouling of said surface.

Method for treating a surface contacted by a fluid compositioncomprising fouling organisms, said method comprising the steps ofcontacting the surface with a composition according to the inventionwith an effective amount of said composition or coating composition,wherein said contacting prevents fouling of said surface, or results ina reduced fouling of said surface.

The above-mentioned surfaces can be at least partly submerged inseawater, or they can be interior or exterior surfaces of a pipe forventilation, or interior walls in a building.

Additional methods in accordance with the present invention are:

Method for disinfecting a surface, said method comprising the steps ofcontacting the surface with a composition according to the inventionwith an effective amount of said composition or coating composition orhygienic composition, wherein said contacting results in a disinfectionof said surface.

Method for removing microbial organisms from a surface, said methodcomprising the steps of contacting the surface with a compositionaccording to the invention with an effective amount of said compositionor coating composition or hygienic composition, wherein said contactingresults in removing microbial organisms from said surface.

Method for coating an object, said method comprising the steps ofcontacting the surface with a composition according to the inventionwith an effective amount of said composition or coating composition orhygienic composition, wherein said contacting results in coating saidobject.

Method for sealing a surface, said method comprising the steps ofcontacting the surface with a composition according to the inventionwith an effective amount of said composition or coating composition orhygienic composition, wherein said contacting results in sealing saidsurface from an external environment.

Method for reducing or eliminating marine corrosion, said methodcomprising the steps of contacting the surface with a compositionaccording to the invention with an effective amount of said compositionor coating composition or hygienic composition, wherein said contactingresults in reducing or eliminating marine corrosion.

Method for preserving a surface, said method comprising the steps ofcontacting the surface with a composition according to the inventionwith an effective amount of said composition or coating composition orhygienic composition, wherein said contacting results in preserving saidsurface.

Method for killing undesirable microbial cells, said method comprisingthe steps of contacting the surface with a composition according to theinvention with an effective amount of said composition or coatingcomposition or hygienic composition, wherein said contacting results inkilling undesirable microbial cells.

Method for generating an antifouling species, said method comprising thesteps of providing a composition comprising at least one enzyme capableof acting on a compound, wherein said action results in the formation ofan antifouling species comprising an antifouling activity, wherein saidcompound does not form part of said composition, further providing saidcompound, and forming said antifouling species by contacting said atleast one enzyme with said compound.

Method for preparing a painting composition according to the invention,said method comprising the steps of providing at least one pigment andat least one enzyme capable of acting on a compound, wherein said actionresults in the formation of an antifouling species comprising anantifouling activity, wherein said compound does not form part of saidcomposition, further providing a carrier for said at least one enzyme,and forming said composition by contacting said at least one enzyme withsaid carrier.

Preferred uses of the invention include, but is not limited to:

Use of at least one enzyme comprising an oxidase activity in themanufacture of a coating composition, wherein said coating compositiondoes not comprise any substrate for said oxidase activity.

Use of at least one enzyme comprising an oxidase activity in a cleaningin place system, wherein said system does not comprise any substrate forsaid oxidase.

The aerogel may be used at the vehicle to distribute proteins in ahydrophobic phase in a molecular disperse distribution not achievable byother means.

The aerogel may be used to influence the rate of polishing for a filmprepared from the mixture

The aerogel can be used to influence the viscosity of the film formingmixture to optimize film formation

In another preferred embodiment the aerogel material described in thepresent invention is used for thermal insulation material.

In another embodiment the aerogel according to this invention is used asa chemical absorber for cleaning up spills. The aerogel can also be usedas a catalyst or a catalyst carrier.

In another embodiment the aerogel is used as an agent in cosmetics.

Resorcinol-formaldehyde aerogels (polymers chemically similar to phenolformaldehyde resins) are mostly used as precursors for manufacture ofcarbon aerogels, or when an organic insulator with large surface isdesired. They come as high-density material, with surface area about 600m²/g.

In an embodiment the invention concerns an antifouling coatingcomposition, for instance a painting composition, for use in theprevention, reduction or removal of fouling of a surface or material. Inan embodiment said surface or material has been submerged in water, suchas sea water or fresh water, and has been fouled by fouling organismsduring said submersion in water. In an embodiment the compositioncomprises an aerogel. In a further embodiment said aerogel comprises atleast one enzyme, such as esterase.

The methods of the present invention may in an embodiment be employed inthe removal, reduction or prevention of fouling resulting fromsubmersion of a material in water, such as seawater or fresh water.

The methods and composition of the present invention are in anembodiment particularly suitable for use in the reduction, prevention orremoval of fouling of materials or surfaces having been submerged inseawater or fresh water, such as for instance ship hulls, buoys or otherstructures being exposed to water.

It is a particular advantage of the present invention that thecompositions and methods of the invention are capable of effectivelypreventing fouling without the use of toxic substances.

EXAMPLES Example 1

The aerogel comprises siliciumoxid. The aerogel is obtained byhydrolysis of tetraalkoxysiloxane dissolved in alcohol. The alcohol issubsequently removed from the generated network by exchange withsupercritical CO2. This solvent can be evaporated without collaps of theaerogel.

The aerogel is obtained by drying of a wet gel. During this process theliquid is removed from the nanopores in the gel. The drying is performedin the presence of supercritical CO2 or another supercritical solvent.It is important to go directly from the liquid phase to a supercriticalphase and subsequently directly from the supercritical phase to a gasphase. An alternative to the supercritic drying is use of DCCA (DryingControl Chemical Additives), ambient pressure drying and freeze drying.

The wet gel is obtained by a SOL-GEL process. The SOL-GEL process istypically performed at temperatures lower than 100° C. For preparationof in-organic gells, typically metaloxides, the reaction typically occurby condensation of metalhydroxides in solution such as they are obtainedby hydrolysis of one or more metalalkoxides. In the first step (referredto as SOL) small independent more or less cross-linked colloid particlesare performed in a colloid suspension. In the second step (referred toas GEL) these colloid particles bind to each other. Thisthree-dimensional network is known as GEL. If the three-dimensionalnetwork is generated from linear polymer chains from the precursorsolution, without a preference for individual particles, a polymer gelis obtained.

Example 2

The aerogel is obtained as described in example 1. The aerogel furthercomprises one or more enzymes and/or one or more other bioactive agents.The one or more enzymes and/or the one or more other bioactive agentsare added to the alcohol during the generation of the network. Thisprocess results in encapsulation of the one or more enzymes and/or theone or more other bioactive agents in the aerogel. The process describedin example 1 may be interrupted after preparation of colloid particlescontaining an enzyme as described in example 2. Completion of thenetwork may be performed under addition of one or more different activecomponents. Hereby the control of spatically distributed activecompounds can be obtained

Example 3

The aerogel is obtained as described in example 1 or 2. The aerogelfurther comprises 1-10% dimethyldialkoxysiloxane to adjust thehydrophobicity of the aerogel. Other alkoxysiloxanes may me used toobtain similar adjustments in hydrophobicity.

Example 4

The aerogel is obtained as describes in example 1, 2 or 3. Si iscompletely or partly replaced with Ti, Al or Boron. This replacementaffects the stability of the aerogel. The replacement can be introducedstatistically. It is possible by preparation of colloid particles toobtain a spatically inhomogeneous aerogel.

Example 5

The aerogel is obtained as describes in example 1, 2, 3 or 4. The one ormore enzymes and/or proteins are modified on amino groups (NH2) and/oron thiol groups (SH) and/or on OH groups. With succinimid,glutaraldehyde or isocyanat groups a desired group can be fixed to theprotein and/or enzyme. In one preferred embodiment polyethylenglycol(PEG) is used as substituent. An alternative to PEG is PEG linked tolong alkyl chain and/or acryl and/or vinyl groups.

Example 6

Esperase has been encapsulated in an aerogel. Tetrapeptide staining hasdemonstrated that Esperase retain its activity after encapsulation intothe aerogel. Heating of the aerogel encapsulating Esperase to 80° C. for24 hour shows that the enzyme activity is retained after the heating.Heating of the aerogel encapsulating Esperase in water to 80° C. for 24hour shows that the enzyme activity is decreased. This demonstrate thatEsperase is stabilised by encapsulation into the aerogel.

Example 7

Two different self-polishing solvent based paints have been formulatedwith aerogels containing two different proteases. Panels with the paintshave been immersed in sea water in Elsinore Harbour, Denmark, for aperiod of 6 months (May-October inclusive). No fouling was observedafter the period, or a very thin layer of algal slime was detectedcompared to controls.

Example 8

Test fields were applied with same kind of formulation containingaerogel and protease on both sides of the rudder of a sailing boat basedin Ishoj Harbour, Denmark. Inspection after the sailing season 6 monthslater showed very thin algal slime and of the same fouling degree as theconventional cupper based antifouling paint.

Example 9

The aerogel is obtained as in examples 1, 2, 3 and 4. The one or moreenzymes/and or proteins are modified on amino groups (NH2) and/or onthiol groups (SH) and or on hydroxyl groups (OH). The substituentinclude a s SiR1R2R3R4 group where R1 links the Si to the enzyme andR2R3 and R4 are chosen among Cl, Br, I and OR5 where R5 is an alkylgroup. A preferred embodiment R5=CH3 and R2=R3=R4=OR5. Hereby the enzymecan be chemically linked into the gel network modifying its lifetime ongel surfaces exposed to water.

Example 10

Enzyme Example of Silicagel, preparation, preparations weight-% weight-%AP29 83.9 16.1 AP34 61.1 38.9 AP35 44.9 55.1 AP32 25.4 74.6

Example 11

Compositions according to the invention were applied to well-definedpanels on a raft and the raft was submerged in water at Elsinoreharbour, Denmark. The raft was submerged for a period of 6 months beforethe results were evaluated. Also included on the raft were panels withconventional paints and controls. The panels of the reafts were treatedas indicated in the following table:

Panels of the test raft Panel 1 Panel 2 Panel 3 Panel 4 Sigma MPT7-Z-APMPT3-Z-AE MPT7-Z-AE Panel 5 Panel 6 Panel 7 Panel 8 MPT7-Z-A MPT3-Z-AEMPT3-ZS-AP SE-ZS-AE Panel 9  Panel 10  Panel 11  Panel 12 MPT3-Z-AMPT7-Z-AP MPT7-Z-AE Mille Xtra

The compositions applied to the raft as indicated in the above tablecontained the following components:

MPT3: Base paint (the figure “3” refers to the amount of rosin inrelation to harpiks extender)MPT7: Base paint (the figure “7” refers to the amount of rosin inrelation to harpiks extender)SE: Solvent epoxy paint

Z: Zink S: Sulphide A: Aerogel P: Polarzyme E: Esperase

Sigma: Positive control (conventional antifouling paint, Sigma cupperbased product+a biocide)Mille Xtra Positive control (conventional antifouling paint, Hempelself-polishing cupper based product)

At the end of the test period of 6 months, the fouling of each panel onthe raft was evaluated by using a score from 0 to 5, where 0 is nofouling growth and 5 is complete coverage of the panel by foulinggrowth. The results were as indicated in the table below. A picture ofthe raft after the experiment is included as FIG. 1. The quantificationsof the below table were based on the picture of FIG. 1.

Quantification of the growth on the panels of the test raft Panel 1Panel 2 Panel 3 Panel 4 0-1 1-2 2 0 Panel 5 Panel 6 Panel 7 Panel 8 2-32 5 5 Panel 9  Panel 10  Panel 11  Panel 12 3 1-2 0-1 2

A conclusion of the test was that the MPT7-Z-AE panels (panels 4 and 11)were least fouled at the end of the test. These panels had been treatedwith the base paint MPT7 comprising aerogel, esperase enzyme and zinc.The MPT7-Z-AE panels proved to be at least as good or possibly evenslightly better than the conventional Sigma cupper-based paint. Thisresult was unexpectedly positive and supports the advantageous effect ofthe present invention. Also, it was evident that the compositionscomprising both aerogel and enzyme (panels 2, 3, 4, 6, 10, and 11) weregenerally better at preventing fouling than the panels comprisingaerogel without enzyme (panels 5 and 9).

Example 12

The rudder from the yacht Erica was painted with 9 different coatings asindicated in the table herein below. The results were evaluated after asailing a season (5 Months) in Danish seawater. The evaluation is aquantification of the growth using a score from 0 to 5, where 0 is nofouling growth and 5 is complete coverage of the panel by foulinggrowth.

Starbord side of rudder Port side of rudder Torm G Solv 6 Solv 10 Solv14 Solv 17 Solv 4 Solv 7 Solv 9 Solv 17 Solv 7  Solv 9  Solv 8 Sovl 8Solv 4 Solv 14 Solv 10 Torm G Solv 6 Evaluation of the test 1 1-2 4 4 51 5 5 5 5 5 1 2-3 3 5 5 1 2

Aerogel with PVC Rosin/ esperase enzyme Activ retarder SOLV 4 0.8 32.8 03:01 SOLV 6 0.2 16.3 7.5:1 SOLV 7 1.1 16.4  03:01 SOLV 8 0.2 freeze-32.7  03:01 dried esperase SOLV 9 0.4 15.2 7.6:1 Comprises silver SOLV10 0.8 16.5  03:01 Comprises silver SOLV 14 0.6 21.4 3.9:1 SOLV 17 0.818.9 3.4:1 TORM G 0.4 27.4 5.4:1

1. An anti-fouling composition for reduction or prevention of fouling ofa surface coated with said composition, said anti-fouling compositioncomprising one or more aerogel(s) and one or more bioactive agent(s)encapsulated in said one or more aerogel(s).
 2. The anti-foulingcomposition comprising one or more aerogel(s) according to claim 1,wherein the one or more aerogel(s) is one or more organic aerogel(s). 3.The anti-fouling composition comprising one or more aerogel(s) accordingto claim 1, wherein the one or more aerogel(s) is one or more in-organicaerogel(s).
 4. The anti-fouling composition comprising one or moreaerogel(s) according to claim 1, wherein the one or more aerogel(s) isone or more silica aerogel(s).
 5. The anti-fouling compositioncomprising one or more aerogel(s) according to claim 1, wherein the oneor more aerogel(s) is one or more carbon aerogel(s).
 6. The anti-foulingcomposition comprising one or more aerogel(s) according to claim 1,wherein the one or more aerogel(s) is one or more metal aerogel(s). 7.The anti-fouling composition comprising one or more aerogel(s) accordingto claim 1, wherein the one or more aerogel(s) has a density in therange from 0.05 to 1.0 g/mol.
 8. The anti-fouling composition comprisingone or more aerogel(s) according to claim 1, wherein the one or moreaerogel(s) has a surface area in the range from 500 m²/g to 2000 m²/g.9. The anti-fouling composition comprising one or more aerogel(s)according to claim 1, wherein the one or more aerogel(s) has a pore sizein the range of from 1 to 25 nm.
 10. The anti-fouling compositioncomprising one or more aerogel(s) according to claim 1, wherein the oneor more aerogel(s) comprises a self-polishing effect.
 11. Theanti-fouling composition comprising one or more aerogel(s) according toclaim 1, wherein the one or more bioactive agent(s) are released fromthe one or more aerogel(s) over time.
 12. The anti-fouling compositioncomprising one or more aerogel(s) according to claim 1, wherein the oneor more bioactive agent(s) comprises one or more protein(s).
 13. Theanti-fouling composition comprising one or more aerogel(s) according toclaim 1, wherein the one or more bioactive agent(s) comprises one ormore enzyme(s).
 14. The anti-fouling composition comprising one or moreaerogel(s) according to claim 13, wherein the one or more enzymescomprises one or more hemicellulolytically active enzyme(s).
 15. Theanti-fouling composition comprising one or more aerogel(s) according toclaim 13, wherein the one or more enzymes comprises one or moreamylolytically active enzyme(s).
 16. The anti-fouling compositioncomprising one or more aerogel(s) according to claim 13, wherein the oneor more enzymes comprises one or more cellulolytically active enzyme(s).17. The anti-fouling composition comprising one or more aerogel(s)according to claim 1, wherein the one or more bioactive agent(s)comprises one or more endopeptidase(s).
 18. The anti-fouling compositioncomprising one or more aerogel(s) according to claim 17, wherein the oneor more endopeptidase(s) comprises a Subtilisin (EC 3.4.21.62).
 19. Theanti-fouling composition comprising one or more aerogel(s) according toclaim 14, wherein the one or more hemicellulolytically active enzyme(s)is selected from the group consisting of Endo-1,4-beta-xylanase (E.C.3.2.1.8), Xylan endo-1,3-beta-xylosidase (E.C. 3.2.1.32),Glucuronoarabinoxylan endo-1,4-beta-xylanase (E.C. 3.2.1.136),Beta-mannosidase (E.C. 3.2.1.25), Mannan endo-1,4-beta-mannosidase (E.C.3.2.1.78) and Mannan endo-1,6-beta-mannosidase (E.C. 3.2.1.101).
 20. Theanti-fouling composition comprising one or more aerogel(s) according toclaim 14, wherein the one or more hemicellulolytically active enzyme(s)comprises a xylanase.
 21. The anti-fouling composition comprising one ormore aerogel(s) according to claim 15, wherein the one or moreamylolytically active enzyme(s) comprises an amylase.
 22. Theanti-fouling composition comprising one or more aerogel(s) according toclaim 13, wherein the one or more enzymes comprises one or morelipase(s).
 23. The anti-fouling composition comprising one or moreaerogel(s) according to claim 1, wherein the composition furthercomprises an esterase.
 24. The anti-fouling composition comprising oneor more aerogel(s) according to claim 1, wherein the composition furthercomprises a protease.
 25. The anti-fouling composition comprising one ormore aerogel(s) according to claim 24, wherein the protease is of thesubtilisin type.
 26. The anti-fouling composition comprising one or moreaerogel(s) according to claim 24, wherein the protease is alcalase. 27.The anti-fouling composition comprising one or more aerogel(s) accordingto claim 1, wherein the composition further comprises a lipase.
 28. Theanti-fouling composition comprising one or more aerogel(s) according toclaim 13, wherein the one or more enzyme(s) comprises one or morehydrolytic enzymes.
 29. The anti-fouling composition comprising one ormore aerogel(s) according to claim 13, wherein the one or more enzyme(s)are functionalized to be actively incorporated into thethree-dimensional structure of the one or more aerogel(s).
 30. Theanti-fouling composition comprising one or more aerogel(s) according toclaim 13, wherein the one or more enzyme(s) are encapsulated in the oneor more aerogel(s) together with one or more other bioactive agent(s).31. The anti-fouling composition comprising one or more aerogel(s)according to claim 1, wherein the composition further comprises a rosin.32. A coating composition comprising the anti-fouling compositioncomprising one or more aerogel(s) according to claim 1 and a carrier.33. The coating composition according to claim 32, wherein the coatingcomposition comprises one or more pigment(s).
 34. The coatingcomposition according to claim 32, wherein the coating compositioncomprises one or more binder(s).
 35. The coating composition accordingto claim 32, wherein the coating composition comprises one or morevehicle(s).
 36. A method for preventing or reducing fouling of asurface, said method comprising the steps of contacting the surface witha composition according to claim 1 with an effective amount of saidcomposition or coating composition or hygienic composition, wherein saidcontacting results in preventing or reducing fouling of said surface.37. A method for preventing or reducing fouling of a surface, saidmethod comprising the steps of contacting the surface with a compositionaccording to claim 32 with an effective amount of said composition orcoating composition or hygienic composition, wherein said contactingresults in preventing or reducing fouling of said surface.
 38. A methodfor preventing or reducing fouling of a surface according to claim 36,wherein the surface is a surface that is at least occasionally immersedin water, wherein said water includes fresh, salt or brackish water. 39.A method for preventing or reducing fouling of a surface according toclaim 37, wherein the surface is a surface that is at least occasionallyimmersed in water, wherein said water includes fresh, salt or brackishwater.
 40. A method for preventing or reducing fouling of a surfaceaccording to claim 36, wherein the surface is selected from surfaces ofvessels including boats and ships, ship hulls, off-shore equipment,pipes, substructures of bridges, piers and aquacultural apparatusesincluding fish farming nets.
 41. A method for preventing or reducingfouling of a surface according to claim 37, wherein the surface isselected from surfaces of vessels including boats and ships, ship hulls,off-shore equipment, pipes, substructures of bridges, piers andaquacultural apparatuses including fish farming nets.
 42. Method forpreparing the composition according to claim 1, said method comprisingthe steps of providing at least one pigment and at least one enzymecapable of acting on a compound, wherein said action results in theformation of an antifouling species comprising an antifouling activity.43. Method for preparing the composition according to claim 32 saidmethod comprising the steps of providing at least one pigment and atleast one enzyme capable of acting on a compound, wherein said actionresults in the formation of an antifouling species comprising anantifouling activity, the method comprises further providing a carrierfor said at least one enzyme, and forming said composition by contactingsaid at least one enzyme with said carrier.